Lagoon

A lagoon is a shallow body of water separated from the ocean or sea by a strip of land, such as a barrier island, coral reef, or sandbank.  Lagoons can be found in coastal areas around the world and are known for their calm, clear waters.  They are typically characterized by their brackish water, which is a mixture of salt and freshwater.  Some lagoons are home to a variety of marine life, such as fish, crabs, and turtles, while others are important habitats for migratory birds.

Lake

A lake is a large body of water surrounded by land. Lakes can be found all over the world, from small ponds to large, freshwater bodies like the Great Lakes in North America.  They are typically fed by rivers and streams and may also have underground springs.  Lakes are important sources of freshwater for people and wildlife, and many are used for recreation, such as swimming, boating, and fishing.

Land Cover

Land cover refers to the physical and biological material on the surface of the Earth, including vegetation, water bodies, and human-made structures. Land cover can vary widely depending on the region and climate, and it is often used to describe the types of ecosystems found in an area.  For example, a forested area would have a different land cover than a desert or grassland.

Land Cover Map

A land cover map is a visual representation of the different types of land cover in a given area.  It typically includes information about vegetation, water bodies, and human-made structures, and can be used to analyze and monitor changes in the landscape over time.  Land cover maps are important tools for understanding the distribution of ecosystems and for managing natural resources, such as forests and wetlands.  They are also used to support land-use planning and conservation efforts.

Land Elevation

Land elevation refers to the height of land above sea level. It is an important topographical feature that can have a significant impact on local climate, hydrology, and ecology.  Land elevation can vary widely, from the highest peaks of mountain ranges to the depths of ocean trenches.  Elevation is typically measured using various methods, such as satellite imagery, aerial photography, or ground-based surveys.

Land Use

Land use refers to the way land is utilized, such as for agriculture, urban development, or conservation.  Land use can have a significant impact on the environment and local communities.  For example, intensive agriculture can lead to soil erosion and nutrient depletion, while urbanization can lead to habitat loss and increased pollution.  Effective land-use planning can help balance competing interests and promote sustainable development.

Landform

A landform is a natural feature on the surface of the Earth, such as a mountain, valley, or plateau.  Landforms are created by various geological processes, such as tectonic activity, erosion, and weathering.  They can be found all over the world and are important components of the natural landscape. Landforms can also have significant ecological and cultural value, such as serving as habitats for wildlife or having spiritual significance for indigenous communities.

Landsat

Landsat is a series of Earth observation satellites launched by the United States Geological Survey (USGS) that provide high-resolution images of the Earth’s surface.  The Landsat program has been in operation since 1972 and has been used for a wide range of applications, including land-use planning, natural resource management, and environmental monitoring.  Landsat imagery is freely available to the public and is used by scientists, policymakers, and the general public to better understand our changing planet.

Landslide

A landslide is a type of mass movement that occurs when a large amount of earth or rock slides downhill.  Landslides can be caused by a variety of factors, such as heavy rain, earthquakes, or human activity.  They can be very destructive, causing damage to infrastructure, homes, and natural landscapes. Landslides can also pose a significant threat to human life, particularly in areas prone to frequent landslides.

Lapilli

Lapilli are small volcanic rock fragments that are ejected during an explosive volcanic eruption.  They are typically between 2 and 64 millimeters in diameter and can travel long distances from the volcano.  Lapilli can cause damage to buildings and infrastructure, and they can also pose a threat to human health, particularly if they are inhaled.

Large Scale Map

A large scale map is a map that shows a small area in great detail.  Large scale maps typically have a scale of 1 10,000 or greater, meaning that one unit on the map represents a smaller distance on the ground.  Large scale maps are useful for detailed planning and analysis, such as urban planning, land-use planning, or emergency response.

Latitude

Latitude is a geographic coordinate that measures the distance of a location north or south of the Earth’s equator.  It is typically measured in degrees, with the equator at 0 degrees and the North and South poles at 90 degrees north and south, respectively.  Latitude is an important factor in determining climate and vegetation patterns, as well as in navigation and mapmaking.  It is also used to define different climate zones, such as the tropics, subtropics, and polar regions.

Lava

Lava is molten rock that flows from a volcano during an eruption.  It can range in temperature from around 700 to 1200 degrees Celsius and can move at speeds of up to several kilometers per hour. Lava can be very destructive, causing damage to buildings, infrastructure, and natural landscapes. However, it can also create new landforms and habitats, such as volcanic islands and lava fields.

Lava Dome

A lava dome is a type of volcanic dome formed by the slow extrusion of viscous lava from a volcano.  Lava domes are typically formed during non-explosive eruptions and can grow over time as more lava is added to the dome.  They can be very unstable and can collapse, leading to pyroclastic flows and other hazards.

Lava Flow

A lava flow is a mass of molten rock that moves down the side of a volcano during an eruption.  Lava flows can be very destructive, causing damage to buildings, infrastructure, and natural landscapes.  However, they can also create new landforms and habitats, such as volcanic islands and lava fields. Lava flows can be very slow-moving, with speeds of just a few meters per hour, or they can be very fast-moving, with speeds of up to several kilometers per hour.

Layer

A layer is a horizontal stratum of rock, soil, or other material that is distinguishable from adjacent layers based on differences in color, texture, or composition. Layers can be formed by a variety of natural processes, such as sedimentation, erosion, and volcanic activity.  They are important for understanding the geological history of an area and can provide clues about past environmental conditions.  Layers can also be important for engineering and construction, as different layers can have different properties that affect their stability and suitability for building.

Legend

A legend is a key or explanatory text on a map, chart, or diagram that explains the symbols or colors used in the illustration.  The legend helps the reader to interpret the information presented and understand what the various symbols and colors represent.  Legends can vary in complexity depending on the type of map or chart and the amount of information being conveyed.

Lens

A lens is a curved piece of glass or other transparent material that can refract light and form an image.  Lenses are commonly used in cameras, telescopes, and microscopes to focus light and create clear images.  They can come in various shapes, such as convex or concave, and can be made from different materials, such as plastic or glass.

Lenticular Clouds

Lenticular clouds are a type of cloud that is shaped like a lens or saucer.  They are commonly found in mountainous regions and are formed by the flow of moist air over the mountains. Lenticular clouds can be very striking and can appear to be stationary, even in strong winds.

Levee

A levee is a natural or artificial embankment or ridge that is built along the banks of a river or other body of water.  Levees are designed to prevent flooding and protect human settlements and agricultural land from the effects of high water.  They can be made from a variety of materials, such as soil, concrete, or rock, and can be reinforced with vegetation or other materials to increase their stability.  However, levees can also be a source of controversy, as they can alter natural water flow patterns and cause unintended consequences downstream.

Level Curve

A level curve, also known as a contour line, is a line on a map that connects points of equal elevation.  Level curves are important for understanding the topography of an area and can help with navigation and planning.  They are commonly used in cartography, engineering, and geology, and can be used to create 3D models of terrain.

Level Line

A level line is a line that is parallel to the horizon and perpendicular to the direction of gravity.  It is used in surveying and engineering to establish a horizontal reference plane for measurements and calculations.  Level lines are important for ensuring accuracy in construction and engineering projects, as they provide a stable reference point for measuring angles, distances, and elevations.

Leveling

Leveling is the process of determining the elevation of a point or surface relative to a known reference point.  It is commonly used in surveying, engineering, and construction to ensure that surfaces are level and that measurements are accurate.  Leveling can be done using a variety of instruments, such as a level, a theodolite, or a laser level.

Lidar

Lidar, short for Light Detection and Ranging, is a remote sensing technology that uses laser light to measure distance and create detailed 3D models of the environment. Lidar can be used for a variety of applications, such as mapping, forestry, geology, and archaeology.  It is particularly useful for creating highly accurate and detailed maps of terrain and other natural features.  Lidar can also be used for autonomous vehicles and robotics, as it can provide precise spatial information about the surrounding environment.

Line

In cartography and geography, a line refers to a continuous mark or series of marks that can represent various features on a map or diagram.  Lines can represent geographic features such as rivers, boundaries, and transportation routes.  They can also be used to represent abstract concepts such as contour lines, which indicate elevation.

Lineament

A lineament is a linear feature on the Earth’s surface, such as a fault, fold, or fracture.  These features can indicate the underlying geologic structures and can be used to better understand the history and evolution of a region.  Lineaments can also be used in geophysical exploration for minerals and hydrocarbons.

Linear Feature

A linear feature is a geographic feature that has a defined length but relatively narrow width.  Examples of linear features include roads, rivers, and ridges. Linear features can be represented as lines on maps and can provide important information about the topography and geology of an area.

Liquefaction

Liquefaction is the process by which soil or other sediment loses its strength and stiffness and behaves like a liquid.  This can occur when an earthquake or other seismic event causes water-saturated sediment to lose its ability to support structures or other loads.  Liquefaction can cause significant damage to buildings and infrastructure and is an important consideration in earthquake engineering and geotechnical engineering. Liquefaction can also occur in other natural disasters such as landslides and volcanic eruptions, and can have serious consequences for human settlements and infrastructure.

Lithology

Lithology is the study of the physical and chemical properties of rocks, including their composition, structure, texture, and origin.  It is an important field of study in geology and is used to identify and classify rocks, understand their formation and distribution, and interpret their geological history. Lithology can also provide insights into the geological processes that have shaped the Earth over time.

Lithosphere

The lithosphere is the solid outer layer of the Earth that includes the crust and uppermost part of the mantle.  It is rigid and brittle and is broken up into a series of tectonic plates that move and interact with each other.  The lithosphere is the site of most geological activity, including earthquakes, volcanoes, and mountain building.

Little Ice Age

The Little Ice Age was a period of global cooling that occurred between the 16th and 19th centuries.  It was characterized by a decrease in global temperatures, particularly in the Northern Hemisphere, and was associated with changes in weather patterns, glacial expansion, and agricultural disruption.  The Little Ice Age had significant impacts on human societies, including crop failures, famine, and population decline.

Littoral Zone

The littoral zone is the area of the shore or coastline that is affected by the tides.  It includes the area between the high tide mark and the low tide mark and can extend inland to include marshes, mudflats, and sand dunes.  The littoral zone is an important ecosystem that supports a wide variety of plant and animal life, including algae, shellfish, and shorebirds.  It is also an important area for human activities such as fishing, recreation, and coastal development.

Loch

A loch is a Scottish term for a body of water, usually freshwater, that is surrounded by land.  It is similar to a lake, but is typically smaller and located in a more remote, rural setting. Lochs are an important part of Scottish culture and landscape, and are often associated with myths, legends, and folklore.

Loess

Loess is a type of wind-blown sediment that is composed of fine-grained particles such as silt and clay.  It is typically light-colored and can form extensive deposits that cover large areas of land.  Loess deposits are often found in regions with a dry, arid climate, and can be several meters thick. They are an important source of information for geologists and archaeologists, as they can provide insights into past climatic and environmental conditions.

Long Profile

A long profile is a type of topographic map that shows the elevation and slope of a river or stream over its entire length. It is created by plotting the elevation of points along the river or stream, and connecting them with a line.  The resulting graph provides a visual representation of the river’s profile, including its gradient, elevation changes, and major features such as waterfalls and rapids.

Longitude

Longitude is a measure of the east-west position of a point on the Earth’s surface, relative to the Prime Meridian.  The Prime Meridian is an imaginary line that runs from the North Pole to the South Pole, passing through Greenwich, England.  Longitude is measured in degrees, with 360 degrees in a full circle. It is an important coordinate in geographic information systems (GIS) and is used to locate points on maps and other geographic data.

Low-relief Map

A low-relief map is a type of topographic map that shows the elevation and slope of a large area, such as a continent or ocean floor, with a low degree of detail. It is typically used to provide a broad overview of the terrain, and may be created using satellite data or other remote sensing techniques. Low-relief maps can be useful for studying large-scale features such as mountain ranges and ocean currents, and for providing context for more detailed maps of smaller regions.