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A saddle refers to a low point between two higher points in a mountain range or ridge.  It resembles the shape of a horse’s saddle and is often a passageway for hikers and animals to travel through.  Saddle points can be challenging to navigate as they are often steep and exposed. In topography, a saddle is also referred to as a col.


Saline is a term used to describe water or soil that contains a high concentration of salt.  Saline water can be found in oceans, seas, and saltwater lakes. It is also present in some groundwater sources. Saline soil is common in arid regions where there is little rainfall and high evaporation rates.  This type of soil is not suitable for growing most crops and can cause damage to vegetation.


Salinity is a measurement of the amount of salt dissolved in water or soil.  It is usually expressed as a percentage or in parts per thousand.  The salinity of water can affect its density, which can impact ocean currents and weather patterns.  Salinity levels can also impact aquatic life, as some organisms can only tolerate certain levels of salt.

Salt Dome

A salt dome is a geological formation that consists of a dome-shaped structure of salt that has risen to the surface from underground.  Salt domes are formed when underground salt deposits are forced upward by the pressure of overlying rock layers.  They can be several kilometers wide and can reach depths of thousands of meters. Salt domes are important sources of salt and can also trap oil and gas deposits.

Salt Flat

A salt flat, also known as a playa, is a flat expanse of land covered in salt and other minerals.  Salt flats are typically found in arid regions where there is little rainfall to dissolve and wash away the minerals.  They are often very reflective and can be quite striking, especially during sunrise and sunset.

Sand Dune

A sand dune is a hill of sand that has been formed by wind or water.  Sand dunes are commonly found in deserts, coastal areas, and near rivers and lakes.  They can vary in size from small ripples to towering mountains of sand.  Sand dunes are constantly shifting due to wind and weather patterns, making them difficult to navigate.


Sandstone is a type of sedimentary rock that is composed of sand-sized grains of mineral, rock, or organic material . It is typically formed in environments such as deserts, beaches, and riverbeds, where sand accumulates and is compacted over time.  Sandstone can vary in color, texture, and hardness depending on the type of minerals that make up the grains.


Saprolite is a type of weathered rock that is formed by the chemical and physical breakdown of bedrock.  It is often found in areas with high rainfall and warm temperatures, where the weathering process is accelerated. Saprolite is soft and crumbly and can be easily excavated with a shovel. It is an important source of soil for agriculture and is also used as a building material.

Satellite Map

A satellite map is a topographical map that has been created using satellite imagery. These maps provide a view of the earth from above and can be used to identify features such as mountains, rivers, and cities.  They are often used for navigation and for studying the earth’s surface.

Saturated Zone

The saturated zone, also known as the phreatic zone, is the area of soil or rock that is completely filled with water.  This zone exists below the water table, which is the level below which the ground is saturated with water.  The depth of the saturated zone can vary depending on the geology of the area and the amount of rainfall.  It is an important source of groundwater, which can be extracted for drinking, irrigation, and other uses.


Scale refers to the ratio of distance on a map to the actual distance on the ground.  It is often expressed as a fraction or a ratio, such as 1 50,000 or 1/50,000. Maps with larger scales, such as 1 10,000, show more detail than maps with smaller scales, such as 1 1,000,000.  Scale is an important consideration when using maps for navigation and for estimating distances.

Scale Bar

A scale bar is a visual representation of the scale of a map. It is typically a line that is marked with distances that correspond to the scale of the map. Scale bars are important for providing a quick and easy reference for the scale of the map and can be used to estimate distances between points on the map.


A scarp is a steep slope or cliff that is formed by erosion or tectonic activity.  Scarp slopes can be found in a variety of environments, including mountains, coastlines, and canyons.  They are often unstable and can be dangerous for climbers and hikers. Scarp slopes can also be important sources of geological information, as they can expose layers of rock and sediment.

Scenic Area

A scenic area is a location that is known for its natural beauty or cultural significance.  Scenic areas can include national parks, beaches, historic sites, and other places that are popular with tourists.  Many scenic areas are protected by governments or non-profit organizations in order to preserve their natural or cultural resources.  Scenic areas are often popular destinations for outdoor activities such as hiking, camping, and wildlife viewing.

Schematic Map

A schematic map is a simplified map that is designed to emphasize specific features or information.  Schematic maps are often used for transportation systems such as subways, airports, and bus routes.  They typically use symbols and simplified shapes to represent landmarks, stations, and other points of interest . Schematic maps can be useful for navigating complex systems, but they may not provide the same level of detail as more traditional maps.


Schist is a type of metamorphic rock that is characterized by its foliated texture.  It is typically formed from shale or other sedimentary rocks that have been subjected to heat and pressure over time.  Schist can be found in a variety of colors and textures and is often used as a decorative stone in building materials.  Schist is also an important source of minerals such as mica and garnet, which are used in a variety of industries.


Scree is a type of loose, fragmented rock that is found on the slopes of mountains and hills . It is formed by the weathering and erosion of larger rocks, which break down into smaller pieces over time.  Scree slopes can be unstable and are often difficult to traverse, making them hazardous for hikers and climbers.


The sea is a large body of saltwater that covers a significant portion of the Earth’s surface . It is home to a wide variety of marine life, including fish, whales, dolphins, and sharks.  The sea is also an important source of food, transportation, and recreation for people around the world.

Sea Cave

A sea cave is a type of cave that is formed by the erosion of rock along the coastline.  They are typically found in areas where the sea has worn away the softer layers of rock, leaving behind a hollowed-out cavity.  Sea caves can be dangerous to explore, as they are subject to tides and waves that can flood the cave and trap visitors.  However, they are also a popular destination for adventurous explorers and photographers, who are drawn to their dramatic beauty and unique geological features.

Sea Chart

A sea chart, also known as a nautical chart, is a map that is designed specifically for use by sailors and navigators.  It provides detailed information about the location of hazards such as reefs, rocks, and shoals, as well as the depth and contour of the seabed.  Sea charts also include information about tides, currents, and other important navigational data.  They are essential tools for anyone who travels by water, from recreational boaters to commercial shipping vessels.

Sea Cliff

A sea cliff is a steep, vertical cliff that is formed by the erosion of rock along the coastline.  They can be found in areas where the sea has worn away the softer layers of rock, leaving behind a sheer face of harder rock.  Sea cliffs are often dramatic and beautiful, but they can also be dangerous to approach or climb, as they are subject to erosion and collapse.

Sea Floor Spreading

Sea floor spreading is the process by which new oceanic crust is formed at mid-ocean ridges and spreads outwards, pushing the existing crust away from the ridge.  This process is driven by magma rising from the Earth’s mantle and solidifying into new crust as it cools. As the new crust spreads outwards, it carries with it the magnetic polarity of the Earth’s magnetic field, providing evidence for the theory of plate tectonics.

Sea Level

Sea level is the average height of the ocean’s surface relative to the Earth’s surface.  It is affected by a variety of factors, including tides, waves, currents, and weather patterns.   Changes in sea level can have significant impacts on coastal communities and ecosystems, particularly in areas that are vulnerable to flooding or erosion.   Rising sea levels, caused by global warming and climate change, are a growing concern for many people around the world.

Sea Stack

A sea stack is a tall, isolated pillar of rock that is formed by the erosion of the coastline by waves and other natural forces.  They are typically found in areas with steep cliffs and rocky shorelines, and are often popular sites for hiking and photography.  Sea stacks can be dangerous to approach or climb, as they are subject to erosion and collapse.

Sea Surface Temperature

Sea surface temperature (SST) is the temperature of the ocean’s surface layer, which can have important effects on weather patterns, ocean currents, and marine ecosystems.  SST is influenced by a variety of factors, including sunlight, wind, and ocean currents, and can vary widely depending on location and time of year.  Changes in SST can have significant impacts on the distribution and abundance of marine species, as well as on human activities such as fishing and shipping.

Sea-floor Topography

Sea-floor topography refers to the shape and features of the ocean floor, including ridges, trenches, and undersea mountains.   It is studied by oceanographers and geologists using a variety of techniques, including sonar mapping and deep-sea submersibles.   Understanding sea-floor topography is important for a variety of reasons, including the study of plate tectonics, the distribution and abundance of marine life, and the exploration of natural resources such as oil and gas.


A seamount is an underwater mountain or volcano that rises at least 1,000 meters above the ocean floor.  They are typically formed by volcanic activity and can be found in all of the world’s oceans.  Seamounts are often important habitats for marine life, as they can provide shelter and food for a wide variety of species.  They are also an important target for scientific study, as they can provide valuable insights into the geological processes that shape the Earth’s crust.


In geology, a section is a vertical slice of rock that exposes its layers for study.  Geologists use sections to analyze the structure, composition, and history of rock formations. Sections are often created by cutting into a hillside, cliff face, or other natural outcrop.  The layers of rock in a section can reveal valuable information about the geological processes that have shaped the Earth’s surface over time.


Sediment is any material that is transported and deposited by wind, water, or ice.  Sediment can consist of a variety of materials, including rock fragments, soil, sand, and organic matter.  It is an important component of the Earth’s surface, as it provides valuable information about geological processes and can be used to reconstruct past environments.  Sediment is also important for the formation of sedimentary rocks, which are a common type of rock that forms through the accumulation and cementation of sediment.

Sedimentary Rock

Sedimentary rock is a type of rock that forms through the accumulation and cementation of sediment.  Sedimentary rocks are formed in a variety of environments, including riverbeds, lakes, oceans, and deserts.  They can be composed of a variety of materials, including sand, clay, and organic matter.  Sedimentary rocks are an important source of information about past environments and geological processes, as they often contain fossils and other evidence of ancient life.


Seepage is the slow movement of water or other fluids through porous materials such as soil or rock.  Seepage can occur naturally, as in the case of groundwater flow, or it can be caused by human activities such as irrigation or waste disposal.  Seepage can have significant impacts on the environment, including the depletion of groundwater resources, the contamination of water supplies, and the erosion of soil and rock.


A seiche is a standing wave that occurs in an enclosed body of water, such as a lake or harbor.  Seiches are caused by a variety of factors, including wind, changes in atmospheric pressure, and seismic activity.  They can have significant impacts on the shoreline, causing erosion and flooding. Seiches can also affect the safety of boats and other watercraft, as they can create dangerous currents and waves.

Seismic Map

A seismic map is a type of map that shows the geological structure and features of an area using seismic data.  Seismic data is collected by sending sound waves through the ground and recording the echoes that bounce back.  This data can be used to create a detailed image of the subsurface geology of an area, including the location of rock formations, faults, and other geological features.  Seismic maps are often used in the exploration and production of oil and gas, as well as in earthquake research.

Seismic Reflection

Seismic reflection is a technique used in geophysics to image the subsurface structure of the Earth.  The method involves sending a sound wave through the ground and recording the echoes that bounce back.  The data collected can be used to create a detailed image of the subsurface geology of an area, including the location of rock formations, faults, and other geological features.  Seismic reflection is widely used in the exploration and production of oil and gas, as well as in earthquake research.

Seismic Wave

A seismic wave is a wave of energy that travels through the Earth’s crust and is caused by earthquakes, explosions, or other sources of energy.  There are two main types of seismic waves body waves and surface waves.  Body waves are the fastest seismic waves and can travel through the Earth’s interior, while surface waves are slower and travel only through the Earth’s surface.  Seismic waves can be measured and analyzed to provide valuable information about the location, magnitude, and characteristics of earthquakes, as well as the structure and composition of the Earth’s interior.


A seismograph is an instrument used to detect and measure earthquakes and other seismic waves.  It consists of a ground-motion detector that is connected to a recording device.  When an earthquake or other seismic activity occurs, the ground motion is recorded by the seismograph, which produces a seismogram, a record of the ground motion.


Seismology is the scientific study of earthquakes and other seismic waves.  It is an interdisciplinary field that includes geology, physics, and engineering. Seismologists use a variety of tools and techniques, including seismographs, to study the causes and effects of earthquakes, as well as to better understand the structure and composition of the Earth’s interior. Seismology is important for earthquake prediction and hazard assessment, as well as for the exploration and production of oil and gas.


Selenite is a type of mineral that is a form of the mineral gypsum.  It is a clear or translucent crystal that often forms in long, thin, bladed shapes. Selenite is commonly found in sedimentary rocks, particularly in evaporite deposits, and is often associated with other minerals such as halite and anhydrite.  Selenite is used in a variety of applications, including in the manufacture of plaster and drywall, as well as in the production of fertilizer and cement.

Semicontinuous Map

A semicontinuous map is a type of map that uses shading or color to represent the distribution of a particular feature or characteristic across an area. Unlike a continuous map, which shows a smooth gradient of values, a semicontinuous map has distinct categories or classes of values that are represented by different colors or shades.  Semicontinuous maps are commonly used in geographic information systems (GIS) to display data such as population density, land use, and vegetation cover.  They are useful for highlighting patterns and trends in data that would be difficult to see on a continuous map.


Semivariogram is a statistical tool used to analyze the spatial variability of a particular phenomenon.  It is commonly used in geostatistics to model spatial dependence and assess the level of uncertainty in a dataset.  The semivariogram graphically represents the average pairwise differences between observations at different distances or lags.  The semivariance is calculated as half the variance of the difference between two observations at a certain distance.

Sensitive Areas

Sensitive areas refer to regions that are particularly vulnerable to human activities, such as development or pollution.  These areas can include wetlands, habitats of endangered species, and other areas with unique or fragile ecosystems.  Governments and organizations often identify sensitive areas and implement measures to protect them, such as creating protected areas or implementing regulations that limit development or pollution in these areas.

Sequent Occupance

Sequent occupance is a concept in geography that describes the idea that places and landscapes have been influenced and shaped by the various human groups that have occupied them over time.  Each group leaves its mark on the landscape through its culture, language, and technology, which can include changes in land use, the built environment, and other aspects of the physical and cultural landscape.  Sequent occupance can help explain the complex histories of places and how they have evolved over time.


Serac is a term used in mountaineering to describe a large block or column of ice that is typically found in a glacier or icefield.  Seracs can be dangerous to climbers because they are unstable and can collapse or topple over without warning.  They are formed when large masses of ice become detached from the glacier or icefield and form vertical columns or pillars.  Seracs are often found on steep slopes or at the base of cliffs, where they can pose a serious hazard to climbers and hikers.


A series is a sequence of rock layers that share similar characteristics and are separated by boundaries called contacts.  The layers within a series are usually deposited during the same geologic time period and can be used to determine the relative ages of the rocks.

Settling Basin

A settling basin is a type of water treatment system that allows suspended particles to settle out of the water before it is discharged into the environment.  It is typically a large, shallow basin where the water is allowed to slow down and the particles are allowed to settle to the bottom.

Sheet Erosion

Sheet erosion is the process of soil erosion that occurs when a thin layer of topsoil is removed by the action of rainfall or running water.  It is often the first stage of erosion and can lead to gully erosion if left unchecked.


A shoreline is the boundary between a body of water and the land, where the two meet.  The shoreline can be a dynamic and ever-changing environment due to the constant interaction between land and water.  The shape and configuration of the shoreline are influenced by a variety of factors such as wave action, tides, sediment deposition, and erosion.


Shelves are commonly found along shorelines and are the shallow areas adjacent to the shore that gradually slope down into the deeper waters of the ocean or lake.  They are formed by the accumulation of sediment, which can be made up of sand, gravel, and other materials.


Shelterbelts are lines of trees or shrubs planted along the edges of agricultural fields, roadways, or other areas to provide protection from wind erosion, wind damage, and soil erosion.  They also provide habitat for wildlife and can improve air and water quality.


In geology, a shield is a large, relatively flat area of exposed Precambrian igneous and metamorphic rocks.  Shields are typically found in the interiors of continents and are some of the oldest rocks on Earth.


Siderite is a mineral that commonly forms in iron-rich environments such as sedimentary rocks or hydrothermal veins. Its name comes from the Greek word “sideros,” meaning iron.  Siderite can range in color from yellow to brown, and its crystal structure is typically rhombohedral. It is also known as iron carbonate and has the chemical formula FeCO3.

Sieve Analysis

Sieve analysis is a technique used in geology to determine the particle size distribution of a soil or sediment sample.  This method involves passing the material through a series of progressively smaller sieves and measuring the amount of material retained on each sieve.  The results of sieve analysis can provide information on the texture and composition of the sample.

Shutter Speed

Shutter speed is a term used in photography to describe the length of time that a camera’s shutter remains open when taking a picture.  This duration is typically measured in fractions of a second, such as 1/250 or 1/1000.  A faster shutter speed results in a shorter exposure time, which can freeze motion or capture sharp images in low-light conditions.  Conversely, a slower shutter speed allows more light to enter the camera, which can result in motion blur or create artistic effects such as light trails.


Silica refers to a mineral compound composed of silicon and oxygen atoms, commonly found in nature in the form of quartz, sand, or flint.  Silica is an important component of many rocks and soils, and is used in a variety of industrial processes, such as the production of glass, ceramics, and electronics.


Silicate is a type of mineral that contains silicon and oxygen atoms, as well as other elements such as aluminum, magnesium, or iron.  Silicates are the most abundant group of minerals in the Earth’s crust, and are found in a wide range of rock types, including granite, basalt, and shale.


Silicification is the process by which silica-rich fluids permeate and replace the original minerals in a rock, resulting in the formation of a new mineral assemblage.  Silicification can occur through a variety of geological processes, such as hydrothermal activity, weathering, or burial diagenesis.


Silicon is a chemical element with the symbol Si and atomic number 14. It is a metalloid with a grayish-white color and a brittle texture.  Silicon is the second most abundant element in the Earth’s crust, after oxygen, and is a key component of many minerals and rocks.  Silicon is also used extensively in the semiconductor industry, where it is used to make computer chips and other electronic devices.


Silt refers to fine particles of sediment that range in size from 1/256 to 1/16 millimeters in diameter.  These particles are larger than clay but smaller than sand. Silt is often deposited by slow-moving water such as rivers and streams, and can also be found in lakes and oceans.


Siltstone is a sedimentary rock that is composed of silt-sized particles that have been compacted and cemented together over time.  It is similar to sandstone but has a finer grain size.  Siltstone is typically gray or brown in color and is often used as a building material due to its durability and resistance to weathering.


A sinkhole is a depression or hole in the ground that is caused by the collapse of the surface layer.  Sinkholes can be caused by a variety of factors, including the dissolution of limestone or other soluble rocks, the collapse of underground mines, or the erosion of soil due to heavy rainfall or poor drainage.  Sinkholes can range in size from small depressions to large craters that can swallow buildings and entire neighborhoods.

Site Analysis

Site analysis is a process that is used to evaluate the physical characteristics and environmental conditions of a particular location. It involves studying factors such as topography, geology, hydrology, vegetation, climate, and human activity in order to understand how they may impact a proposed development or construction project.  Site analysis is an important step in the design process as it can help to identify potential challenges and opportunities for a project, and inform decisions about site layout, orientation, and materials.


Skarn is a type of rock that forms at the contact between igneous and sedimentary rocks.  It is characterized by a distinct mineral assemblage that includes calcite, garnet, and pyroxene.  Skarn deposits are often associated with hydrothermal mineralization and can be an important source of copper, gold, and other metals.

Slaty Cleavage

Slaty cleavage is a type of foliation that is commonly found in fine-grained sedimentary rocks such as shale and slate.  It is caused by the alignment of clay minerals or other fine-grained particles in the rock, which gives it a characteristic layered appearance.  Slaty cleavage can be used to identify the direction and intensity of deformation in the rock, and is an important factor in the formation of geological structures such as folds and faults.


Slope refers to the inclination or angle of a surface, such as the side of a hill or the surface of a roof. It is commonly measured in degrees or as a ratio of vertical distance to horizontal distance.  Slope is an important factor in many geological and engineering applications, such as the stability of slopes and the design of drainage systems.  Slope can also be used to describe the gradient of a stream or river, which can have important implications for erosion and sediment transport.


A slump is a type of mass wasting that occurs when a block of soil or rock slides along a curved surface.  It is often triggered by heavy rainfall or other disturbances that cause the slope to become unstable.  Slumps can vary in size from small earthflows to large landslides that can cause significant damage to infrastructure and communities.  Slumps are an important factor in geohazard assessments and can be mitigated through various engineering measures such as slope stabilization and drainage systems.

Small Scale Map

A small scale map is a map that shows a large area with less detail.  It typically covers a large region, such as a state or country, and has a low level of resolution.  Small scale maps are commonly used for planning and orientation purposes, and can help users to understand the layout and relationships between different geographic features.  They are also useful for showing broad patterns and trends over a large area, such as population density or climate zones.

Snow Line

The snow line is the elevation above which snow and ice persist throughout the year.  It is also known as the permanent snow line and varies depending on latitude, altitude, and other factors.  The snow line is an important factor in many geological and ecological processes, as it influences the distribution of plants and animals, the formation of glaciers and ice caps, and the availability of freshwater resources.


A snowfield is a large expanse of snow that is typically found at high elevations or in polar regions.  Snowfields can vary in size from a few meters to hundreds of kilometers, and are an important component of many mountain ecosystems.  They play a crucial role in regulating the water cycle, as they store and release water in the form of snowmelt.  Snowfields also provide habitat for a variety of species, including arctic foxes, snowshoe hares, and polar bears.


Soil is a mixture of organic and inorganic materials that covers the surface of the earth. It is formed by the weathering and decomposition of rocks and other materials, and is a critical component of many ecosystems.  Soil provides the nutrients and water that plants need to grow, and is also important for supporting a variety of other organisms, including fungi, bacteria, and insects.  Soil can vary widely in composition and fertility, depending on factors such as climate, topography, and vegetation cover.  It is an important resource for agriculture and forestry, and can also play a role in mitigating climate change through carbon sequestration.

Soil Horizon

A soil horizon is a layer of soil that is characterized by a distinct set of properties, such as texture, color, and organic content.  There are several different types of soil horizons, including the topsoil, subsoil, and parent material.  Each horizon has a different role in the soil ecosystem, and plays an important role in supporting plant growth and other ecological processes.

Soil Moisture

Soil moisture refers to the amount of water that is held within the soil.  It is an important factor in many ecological and agricultural processes, as it influences plant growth, soil erosion, and nutrient cycling.  Soil moisture can vary widely depending on factors such as climate, vegetation cover, and soil texture.  It is typically measured using specialized instruments such as soil moisture sensors or tensiometers.

Soil Profile

A soil profile is a vertical section of soil that shows the different soil horizons and other features such as roots and rocks.  It provides a detailed look at the composition and structure of the soil, and can be used to identify the different layers and their properties.  Soil profiles are important for understanding soil formation and development, and can be used to make decisions about land use and management.

Soil Survey

A soil survey is a systematic examination and inventory of the soils in a particular area.  It typically involves mapping the different soil types, identifying their properties and characteristics, and assessing their suitability for different land uses.  Soil surveys are an important tool for agriculture, forestry, and land use planning, as they can help to inform decisions about soil management, conservation, and restoration.  They are often conducted by government agencies or research organizations, and can involve a range of field and laboratory techniques.


A solstice is an astronomical event that occurs twice a year, when the tilt of the earth’s axis is either closest or furthest from the sun.  The solstices mark the beginning of summer and winter in the northern hemisphere, and the beginning of winter and summer in the southern hemisphere. During the solstice, the duration of daylight is at its longest or shortest, depending on the hemisphere.


Sonar is a technology that uses sound waves to detect and locate objects underwater.  It works by emitting a sound wave and then measuring the time it takes for the sound to bounce back after hitting an object.  Sonar is commonly used in oceanography, marine biology, and underwater navigation, and has a range of applications in military, commercial, and scientific contexts.


Soundings refer to measurements of the depth of a body of water.  They are typically taken using specialized equipment such as sonar or echo sounders, and are used to create maps and charts of the seabed or lakebed.  Soundings can also be used to measure the thickness of ice, the depth of a well, or the elevation of a riverbed.


In geography, the source refers to the starting point of a river or stream.  It is the place where the water begins its journey, typically at a high elevation or in a mountainous area. The source can be a spring, a glacier, or a combination of sources, and is an important factor in determining the characteristics of the river or stream.  The source is often identified and studied by hydrologists, geographers, and other scientists, as it can provide important information about water resources, ecosystems, and land use.

Source Rock

A source rock is a type of sedimentary rock that contains organic material, such as plant and animal remains, which can be transformed into oil or gas through heat and pressure over millions of years.  Source rocks are an important component of petroleum geology, as they provide the raw material for the formation of oil and gas reservoirs.  They are typically found in areas with a high level of organic productivity, such as shallow marine environments.

South Seeking Arrow

A south-seeking arrow is a device used for navigation that indicates the direction of the Earth’s magnetic south pole.  It works by aligning with the magnetic field of the Earth, which is used by navigators to determine their orientation and direction.  South-seeking arrows are commonly used in compasses, which are essential tools for navigation both on land and at sea.

Southern Hemisphere

The Southern Hemisphere is the half of the Earth that is south of the equator.  It includes the continents of Antarctica, Australia, South America, and parts of Africa.  The Southern Hemisphere has a unique set of environmental conditions, including different seasons, weather patterns, and ecosystems. It is home to many iconic species such as penguins, kangaroos, and the southern right whale.

Space Weathering

Space weathering refers to the physical and chemical changes that occur on the surface of solid bodies in the solar system, such as asteroids, comets, and the Moon, as a result of exposure to cosmic radiation and other environmental factors.  Space weathering can alter the appearance and composition of these bodies, and can provide important information about the history and formation of the solar system.  Scientists use a range of techniques, including remote sensing and laboratory analysis, to study the effects of space weathering on these objects.


A spall is a small fragment of rock that breaks off a larger rock due to weathering or other natural processes.  Spalls can be found on the surface of rock formations, and are often used as building materials in traditional construction.  Spalls can also be caused by human activity, such as blasting or quarrying.

Spatial Data

Spatial data refers to information that is related to a specific location or geographic area.  This can include data on land use, topography, population, climate, and many other factors.  Spatial data is often used in GIS (Geographic Information System) software, which allows users to create maps and analyze data in a spatial context. Spatial data is used in a variety of fields, including urban planning, environmental science, and natural resource management.

Species Diversity

Species diversity refers to the number and variety of species that exist in a given area or ecosystem. H igh species diversity is often seen as a sign of a healthy ecosystem, as it indicates a wide range of ecological niches and a balance of species interactions.  Species diversity can be affected by a range of factors, including climate, habitat loss, and human activity.  Measuring and monitoring species diversity is an important part of conservation biology and environmental management.

Specific Gravity

Specific gravity is a measure of the density of a material compared to the density of water.  It is typically expressed as a ratio or a decimal, and is used in many fields, including geology, chemistry, and engineering.  Specific gravity is often used to identify minerals and rocks, as different minerals have different specific gravities.  It is also used to determine the quality of materials such as concrete and asphalt, as materials with a higher specific gravity tend to be stronger and more durable.

Spherical Projection

A spherical projection is a way of representing the Earth’s surface as a flat map.  Unlike other types of map projections, such as cylindrical or conic projections, a spherical projection attempts to preserve the true shape and size of landmasses and bodies of water.  However, because it is impossible to represent a three-dimensional surface on a two-dimensional map without some distortion, a spherical projection still has some distortions, particularly around the poles.

Spheroidal Weathering

Spheroidal weathering is a type of weathering that occurs on rocks that have a spherical or ellipsoidal shape, such as boulders or pebbles.  It occurs when water and other weathering agents penetrate into the rock along joints or fractures and dissolve minerals, causing the rock to break down into rounded shapes.  This type of weathering is common in areas with high rainfall and high humidity, as the water can penetrate more easily into the rock.


A spillway is a structure built to control the flow of water from a reservoir or dam.  It is designed to prevent the water from overflowing the top of the dam and causing flooding downstream.  A spillway can be either a natural or artificial structure, and it typically includes a channel or chute that allows water to flow safely away from the dam.  The design of a spillway depends on the size and shape of the reservoir or dam, as well as the expected volume and velocity of the water flow.


A spring is a natural source of water that flows to the surface from underground.  Springs can occur in a variety of settings, including mountains, valleys, and coastal areas.  They are formed when underground water is forced to the surface due to pressure from rock formations, or when the water table intersects with the surface of the Earth.  Springs can be a valuable source of drinking water, and they also provide important habitat for a variety of plants and animals.  Springs can be classified based on their flow rate and the temperature of the water they produce.

Spring Tide

A spring tide is a type of tide that occurs when the Sun, Moon, and Earth are aligned, creating a stronger gravitational pull on the Earth’s oceans.  This results in higher high tides and lower low tides than normal, which can lead to flooding in low-lying areas.  Spring tides occur approximately twice a month, during the new and full moon phases.


A stalactite is a mineral deposit that forms on the ceiling of a cave or other underground space.  It is formed by water dripping from the ceiling and leaving behind mineral deposits, usually calcium carbonate.  Over time, the mineral deposit grows, forming a cone-shaped structure that hangs down from the ceiling.  Stalactites can vary in size and shape, and they are often used as indicators of the age and history of a cave.


A stalagmite is a mineral deposit that forms on the floor of a cave or other underground space.  It is formed by water dripping onto the floor and leaving behind mineral deposits, usually calcium carbonate.  Over time, the mineral deposit grows, forming a cone-shaped structure that rises up from the floor. Stalagmites can vary in size and shape, and they are often used as indicators of the age and history of a cave.

Standard Deviation

Standard deviation is a statistical measure that indicates the amount of variation or dispersion in a set of data.  It is calculated by determining the square root of the variance, which is the average of the squared differences from the mean.  A high standard deviation indicates that the data points are widely spread out, while a low standard deviation indicates that the data points are closely clustered around the mean.  Standard deviation is often used in fields such as economics, finance, and science to measure the degree of uncertainty or risk associated with a particular data set.

State Plane Coordinate System

The State Plane Coordinate System (SPCS) is a coordinate system used in the United States to describe the location of points on the Earth’s surface.  It divides the country into different zones, each with a unique projection and coordinate system, allowing for more accurate and precise measurements. The SPCS was developed by the National Geodetic Survey (NGS) and is commonly used in land surveying, mapping, and engineering projects.  Each state has its own set of coordinate zones, with some states having multiple zones to account for variations in their terrain.

Statistical Analysis

Statistical analysis is a method used to analyze and interpret data in order to draw conclusions and make informed decisions.  It involves collecting, organizing, and interpreting numerical data using various statistical techniques such as regression analysis, hypothesis testing, and probability theory. Statistical analysis is commonly used in fields such as economics, social sciences, and medical research to identify patterns, relationships, and trends in data. It can be used to make predictions, test hypotheses, and inform decision-making processes.

Steep Slope

A steep slope is an incline or gradient that is greater than average or normal.  It is commonly defined as a slope with a gradient greater than 45 degrees or a rise to run ratio of 2 1 or more.  Steep slopes can pose challenges for construction, transportation, and other activities, and may require specialized engineering techniques or equipment to safely navigate or work on.  They are also important features of the natural landscape, influencing factors such as erosion, water flow, and vegetation distribution.  Steep slopes can be found in a variety of settings, including mountainous regions, cliffs, and river valleys.

Stereographic Projection

A stereographic projection is a mapping technique used to represent a three-dimensional object or surface onto a two-dimensional plane.  It is commonly used in geology, crystallography, and cartography to depict the orientation of planes and lines in space.  The stereographic projection places the object or surface on a transparent sphere and projects it onto a tangent plane.  This allows for easier visualization of the object’s features and helps to identify relationships between different planes and lines.


A stereonet is a special type of graph paper used in geology and structural analysis.  It is used to plot the orientation of geological features, such as folds and faults, and to analyze the geometry of rock formations.  The stereonet is a projection of a sphere onto a two-dimensional plane, with a grid of lines representing the orientation of planes and lines in three-dimensional space.


Stochastic refers to a process or system that involves random or probabilistic elements. It is used in many fields, including finance, engineering, and science, to model complex systems where outcomes are uncertain.  Stochastic models often use statistical analysis to predict the likelihood of different outcomes based on probability distributions.


In geology, a stock is a small, intrusive igneous body that is usually less than 100 square kilometers in size.  It is typically located in the upper crust and is composed of coarse-grained rocks such as granite or diorite.  Stocks are often associated with larger igneous intrusions, such as batholiths or plutons, and can be used to study the geologic history and composition of an area.  Stocks are also important targets for mineral exploration, as they can contain valuable mineral deposits.


Stockwork is a geological term used to describe a complex network of interconnected mineral veins that fill the fractures and cavities in a rock mass. The term “stockwork” is derived from the German word “Stock,” meaning a stick or branch, which refers to the branching nature of the veins.  This network of veins is often found in regions where the rock has undergone intense fracturing due to tectonic activity or other geological forces.


Strata refers to layers of rock that have been deposited over time, with each layer representing a distinct period in geological history.  These layers can be made up of a variety of different materials, including sediment, volcanic ash, and even organic matter.  The study of these layers and their composition can provide insight into the geological history of a region, including the environmental conditions that existed during different time periods.


Stratification is the process by which sedimentary rocks are formed from the deposition of sediment in layers.  This process occurs when sediment is deposited in a body of water, such as a lake or ocean, and settles to the bottom over time.  As more sediment is deposited, distinct layers begin to form, with each layer representing a specific period of time.  These layers can be studied to determine the environmental conditions that existed during different time periods.


Stratigraphy is the study of the layers of rock that make up the Earth’s crust.  This field of study is concerned with the relationships between different layers of rock and the environmental conditions that existed during the time of their deposition.  Stratigraphers use a variety of tools and techniques to study these layers, including geologic maps, aerial photographs, and satellite imagery.


A stratum is a single layer of rock that has been formed through the process of sedimentation.  Strata are often found in sedimentary rocks and can be used to study the geological history of a region.  By examining the composition of different strata, geologists can gain insight into the environmental conditions that existed during the time of their formation.


A stream is a body of water that flows through a channel, typically originating from a source such as a spring or glacier.  Streams are typically smaller than rivers and may be fed by other smaller streams or tributaries.  They are an important component of many ecosystems and play a vital role in the water cycle.

Stream Channel

The stream channel is the physical pathway through which a stream flows.  It is the bed of the stream, which is formed by the erosion and transport of sediment by the flowing water.  The channel can vary in size and shape depending on the volume and speed of the water, as well as the type of sediment that is being transported.

Stream Order

Stream order is a measure of the hierarchy of streams within a river system.  The order of a stream is determined by the number of tributaries that flow into it. A first-order stream has no tributaries, while a second-order stream has one or more first-order streams flowing into it.  Higher order streams are formed when two or more streams of the same order merge together.

Stream Piracy

Stream piracy is a phenomenon that occurs when a stream or river diverts the flow of another stream or river.  This can occur when a stream erodes through a divide, causing water to flow into a neighboring stream or river.  Stream piracy can have significant impacts on the ecosystems of the affected streams, as well as on human activities such as agriculture and hydroelectric power generation.

Stream Terrace

A stream terrace is a flat or nearly flat area adjacent to a stream that is elevated above the current stream channel.  Stream terraces are formed over time as a result of changes in the stream’s flow and erosion patterns.  These features can provide important information about the geologic history of the region, including past flood events and changes in the course of the stream.


Streamflow refers to the movement of water in a stream or river.  It is typically measured in cubic feet per second and can vary depending on factors such as precipitation, snowmelt, and groundwater discharge.  Streamflow is an important factor in the health and stability of ecosystems, as well as in the management of water resources for human activities.


Striations are grooves or scratches on the surface of a rock or other hard material.  They are typically caused by the movement of glaciers or other forces that cause rocks to rub against each other.  Striations can provide important information about the direction and intensity of past glacial movement and are often used in the study of glacial geology.


In geology, the term strike refers to the orientation of a rock layer or fault relative to the horizontal plane.  It is measured by the angle between the layer or fault and a horizontal line, and is typically expressed in degrees.  The strike can provide important information about the structure and composition of rock formations, and is an important factor in the exploration and extraction of natural resources such as oil and gas.

Structural Contour Map

A structural contour map is a type of geologic map that displays the surface distribution of rock units based on their elevations relative to a common datum.  The contours on the map represent lines of equal elevation, and can be used to infer the shape and orientation of subsurface rock formations. Structural contour maps are commonly used in the exploration and production of oil and gas, as well as in the study of geologic hazards such as earthquakes and landslides.


In geology, structure refers to the arrangement or orientation of rock units or other geologic features.  Structural features can include faults, folds, and joints, as well as more subtle features such as bedding planes and cleavage.  The study of structure is an important part of geology, as it can provide insights into the history and evolution of a particular area, as well as into the location and potential for natural resources such as minerals and groundwater.


Subduction is a process by which one tectonic plate is forced beneath another as they move relative to each other.  This process is typically associated with convergent plate boundaries, where two plates are moving towards each other.  Subduction can cause a variety of geologic phenomena, including earthquakes, volcanic eruptions, and the formation of mountain ranges.

Subduction Zone

A subduction zone is a type of convergent plate boundary where one tectonic plate is forced beneath another.  Subduction zones are typically marked by deep ocean trenches, which are formed by the bending of the subducting plate as it descends into the mantle.  Subduction zones are associated with a wide range of geologic hazards, including earthquakes, tsunamis, and volcanic eruptions.


Subsidence is the sinking or settling of the ground surface, typically as a result of natural or human-induced factors.  Natural subsidence can occur due to factors such as soil compaction, erosion, and geological processes.  Human-induced subsidence can be caused by activities such as groundwater withdrawal, oil and gas extraction, and the construction of buildings and other infrastructure.


Sulfur is a chemical element with the symbol S and atomic number 16.  It is a nonmetal that occurs naturally in elemental form or in minerals such as gypsum and pyrite.  Sulfur is an important element in many industrial processes, including the production of fertilizers, chemicals, and pharmaceuticals. It is also used as a component of gunpowder and as a preservative in the food industry.


The summit is the highest point of a mountain or hill. It is typically marked by a distinct peak or ridge, and can offer panoramic views of the surrounding landscape.  The summit can be reached by hiking or climbing, and is often a destination for outdoor enthusiasts seeking adventure and natural beauty.

Sun Angle

Sun angle refers to the angle at which the sun’s rays strike the Earth’s surface.  It is determined by the angle between the horizon and the sun, and can vary depending on factors such as the time of day, the season, and the latitude of the location.  Sun angle can have important implications for a range of activities, including agriculture, construction, and outdoor recreation.  It can also influence the amount of solar energy that is absorbed by the Earth’s surface, which is important for understanding climate and weather patterns.

Sun Path

The sun path refers to the daily and seasonal path of the sun across the sky, as viewed from a particular location on Earth.  The sun’s path is influenced by factors such as the Earth’s rotation and its position in relation to the sun, and can have important implications for a range of activities, including agriculture, architecture, and solar energy production.  Understanding the sun path is essential for optimizing the design and performance of solar energy systems, as well as for predicting and planning for changes in the availability of sunlight.


In geology, a supergroup is a unit of rock that contains several formations or groups of formations.  Supergroups are typically composed of sedimentary rocks that were deposited during a specific time interval, and can be used to infer the geologic history of an area.  They are often named for the dominant rock type or stratigraphic unit within the supergroup.


Superposition is a principle of relative dating in geology, which states that in a sequence of sedimentary rocks, the oldest layer is at the bottom and the youngest layer is at the top.  This principle is based on the observation that in undisturbed rock layers, the older layers are typically buried beneath younger layers as a result of the continuous deposition of sediment over time.  Superposition is a fundamental principle of geology, and is used to determine the relative ages of rocks and to infer the geologic history of an area.


Supersaturated refers to a solution that contains more of a dissolved substance than would normally be possible under the given conditions. Supersaturation can be achieved by adding more solute to a solution than it can dissolve, or by changing the temperature or pressure of the solution. Supersaturated solutions are often unstable and can spontaneously precipitate out excess solute under certain conditions.  Supersaturation is a key concept in chemistry, and is used in a range of industrial and scientific applications, including in the production of pharmaceuticals, semiconductors, and food products.

Surf Zone

The surf zone is the area where waves break as they approach the shore.  The surf zone is typically characterized by strong currents, turbulent water, and sandy or rocky seabeds.  The surf zone is an important ecological habitat, supporting a variety of marine species, and is also a popular location for recreational activities such as surfing, swimming, and fishing.

Surface Water

Surface water refers to water that is found on the Earth’s surface, including rivers, lakes, streams, and ponds.  Surface water is an important resource for human societies and ecosystems, providing drinking water, irrigation water, and habitat for aquatic plants and animals.  Surface water is subject to a range of environmental pressures, including pollution, climate change, and overuse, and its management and protection are critical for sustaining human and ecological wellbeing.

Surrogate Surface

A surrogate surface is a representation of a natural or constructed surface that is used to simulate or model its behavior under different conditions. Surrogate surfaces are often used in laboratory or computer simulations to study the physical or chemical processes that occur at the surface, and to develop predictive models of surface behavior.  Examples of surrogate surfaces include glass slides, silicon wafers, and modified surfaces that are designed to mimic the properties of natural surfaces such as plant leaves or animal skins.


Surveying is the practice of measuring and mapping the Earth’s surface and subsurface features using a variety of tools and techniques. Surveying is used in a wide range of applications, including construction, engineering, land management, and environmental monitoring.  Surveying techniques include using surveying instruments such as theodolites and total stations, as well as global positioning system (GPS) technology and remote sensing techniques such as LiDAR and aerial photography.  Accurate surveying is essential for ensuring the safety and efficiency of infrastructure projects, as well as for managing natural resources and protecting the environment.

Suspended Load

Suspended load is a term used in fluvial geomorphology to describe the sediment particles that are carried in suspension by flowing water.  These sediment particles are typically smaller than the grains of sand and gravel that are moved along the riverbed as bed load. Suspended load can include fine silt and clay particles that remain in suspension for long periods of time, as well as organic matter such as leaves and twigs.  The amount and composition of suspended load in a river system can have important ecological and hydrological implications, influencing the water quality, nutrient cycling, and habitat availability for aquatic organisms.


A swamp is a type of wetland ecosystem characterized by standing water and a high density of woody vegetation such as trees and shrubs.  Swamps are typically found in low-lying areas with poor drainage, and are often associated with river floodplains and coastal regions.  Swamps are important habitats for a wide variety of plant and animal species, including amphibians, reptiles, birds, and mammals. Swamps can also provide important ecosystem services, such as carbon storage, water purification, and flood control.


A symbol is a graphic representation of an object, idea, or concept. Symbols are widely used in cartography, where they are used to represent geographic features such as rivers, mountains, and buildings.  Symbols are also used in many other fields, including mathematics, science, and literature. Symbols can be simple or complex, and can have multiple meanings depending on the context in which they are used.


A syncline is a type of fold in rock layers where the layers dip inward, creating a U-shaped trough.  Synclines are typically formed by compressive forces that push the layers of rock together, causing them to fold and buckle.  Synclines can be found in a variety of geological settings, including mountain ranges, sedimentary basins, and volcanic regions.  Synclines often contain valuable mineral deposits, as the folding and deformation of the rock layers can create traps that concentrate minerals.

Synthetic Aperture Radar

Synthetic aperture radar (SAR) is a remote sensing technology that uses radar to create high-resolution images of the Earth’s surface.  SAR works by transmitting a radar signal towards the Earth’s surface and then recording the signal that is reflected back.  By analyzing the time delay and frequency of the reflected signal,  SAR can create detailed images of the surface features, including topography, vegetation, and buildings.  SAR is used in a variety of applications, including geological mapping, agriculture monitoring, and disaster response.

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