Ice Cap

An Ice Cap is a small ice sheet located in a high altitude area that covers the top of a mountain peak.  These caps are formed from the accumulation of snow and ice, which slowly compresses over time. Ice Caps are found in polar regions, as well as in the high mountain regions of the world.  They are typically less than 50,000 square kilometers in size and have a thickness of less than 500 meters.  The Greenland Ice Cap is the largest ice cap in the world, covering an area of over 1.7 million square kilometers.

Ice Field

An Ice Field is a large expanse of interconnected glaciers and ice sheets that form in high altitude areas.  These fields are typically found in the polar regions and high mountain ranges of the world. Ice Fields are often located at the base of a mountain range and are fed by the accumulation of snow and ice.  They can cover an area of up to 50,000 square kilometers and can have a thickness of several hundred meters.  The Columbia Icefield in Canada is one of the largest Ice Fields in North America.

Ice Front

An Ice Front is the leading edge of an advancing glacier or ice sheet.  This is the point where the ice meets the sea or land and begins to break apart or melt. Ice Fronts can be found in polar regions, as well as in high altitude areas.  They are often characterized by large chunks of ice breaking off and falling into the water.  Ice Fronts are an important indicator of climate change, as they are known to be receding in many parts of the world due to global warming.

Ice Sheet

An Ice Sheet is a large, thick expanse of ice that covers a significant portion of a continent or island.  Ice Sheets are found in polar regions, such as Antarctica and Greenland, and are formed from the accumulation of snow and ice over thousands of years.  They can cover an area of up to 14 million square kilometers and can have a thickness of several kilometers.  Ice Sheets are an important indicator of climate change, as they are known to be melting at an accelerating rate due to global warming.

Igneous Rock

Igneous rock is a type of rock that forms from the cooling and solidification of magma or lava.  Magma is molten rock beneath the Earth’s surface, while lava is molten rock that has erupted onto the surface. Igneous rocks can be either intrusive or extrusive.  Intrusive igneous rocks form when magma cools slowly beneath the Earth’s surface, while extrusive igneous rocks form when lava cools quickly on the surface.  Examples of igneous rocks include granite, basalt, and pumice.

Impact Crater

An impact crater is a circular depression on the surface of a planet, moon, or other celestial body that is caused by the impact of a meteorite or other object from space. Impact craters can range in size from a few meters to hundreds of kilometers in diameter.  They are often characterized by a raised rim and a central depression, known as the crater floor.  The largest known impact crater on Earth is the Vredefort Crater in South Africa, which is approximately 300 kilometers in diameter.

Incline

Incline refers to the slope or angle of a surface, typically in reference to a hill or slope.  The degree of incline is measured in degrees or as a percentage, which represents the rise over the run of the surface. Incline is an important factor in many fields, including engineering, construction, and sports.  For example, a steep incline on a ski slope can make it more challenging for skiers, while a gentle incline on a roadway can make it easier for vehicles to climb.

Inclinometer

An inclinometer is an instrument that is used to measure the angle of incline or slope of a surface. Inclinometers are commonly used in construction, engineering, and geology to measure the angle of a slope or the tilt of a surface.  They can be either digital or analog, and are often designed to be portable and easy to use.  Inclinometers can also be used in vehicles, such as airplanes and ships, to measure the angle of inclination and help with navigation.

Index Map

An Index Map is a map that provides an overview of a larger area, typically a region or country, and indicates the location and extent of individual maps within that area.  Index maps are commonly used in cartography to help users locate and navigate through large map collections.  They often include a grid system or reference marks to assist with the location of a specific map.  Index maps can also be used in geographic information systems (GIS) to provide an overview of spatial data and assist with data management and analysis.

Inertial Navigation

Inertial Navigation is a method of navigation that uses accelerometers and gyroscopes to determine the position and velocity of a moving object.  This method of navigation is commonly used in aviation, aerospace, and military applications, as well as in autonomous vehicles and robotics.  Inertial Navigation systems rely on the principles of Newtonian physics to measure changes in the object’s motion and calculate its position and velocity relative to a known starting point.

Infiltration

Infiltration is the process by which water enters and moves through the soil or other porous materials.  This process is important in hydrology, as it affects the movement and distribution of water in the environment. Infiltration rates are influenced by factors such as soil type, slope, vegetation, and land use.  Excessive infiltration can lead to soil erosion, flooding, and landslides, while insufficient infiltration can lead to drought and water scarcity.

Inflow

Inflow refers to the movement of water or other fluids into a system or container. In hydrology, inflow is often used to describe the amount of water that enters a water body, such as a lake or river, from a specific source, such as a tributary or groundwater.  Inflow rates can be influenced by factors such as precipitation, land use, and topography.  Inflow is an important factor in the management and conservation of water resources, as it affects the quantity and quality of water available in a given area.

Infrared Aerial Photography

Infrared Aerial Photography is a method of capturing images from the air using sensors that detect infrared radiation.  This type of photography can be used in a variety of applications, such as agriculture, environmental monitoring, and military surveillance. Infrared aerial photography can provide valuable information about the health and condition of vegetation, the presence of water, and the distribution of heat.  It is often used in conjunction with other types of aerial photography, such as visible light and multispectral photography, to provide a more complete understanding of the area being studied.

Inlet

An inlet is a body of water that is connected to a larger body of water, such as a lake or ocean, and is typically narrower and shallower than the body of water it is connected to.  Inlets can form in a variety of ways, such as through erosion or tectonic activity.  They are often characterized by strong currents, as water flows in and out with the tides. Inlets can provide important habitat for aquatic plants and animals, and are often used for recreation, such as boating and fishing.

Inlier

An inlier is a geological formation that is surrounded by rocks or sediments of a different type or age. Inliers can provide valuable information about the geologic history of an area, as they can expose older rock formations that have been eroded away in surrounding areas. Inliers can also provide important habitat for plants and animals that are adapted to the unique conditions found in these formations.

Inner Gorge

An Inner Gorge is a narrow, steep-walled canyon that is typically located at the bottom of a larger canyon or valley. Inner gorges can form through a variety of geologic processes, such as erosion by water or glaciation.  They are often characterized by vertical cliffs, cascading waterfalls, and turbulent rapids. Inner gorges can provide important habitat for a variety of plant and animal species, and are often used for recreation, such as hiking and rafting.

Inselberg

An Inselberg is a prominent, isolated rock hill or mountain that rises abruptly from a plain or lowland. Inselbergs are typically composed of hard, erosion-resistant rocks, such as granite or sandstone, that have resisted weathering and erosion while the surrounding rocks have been worn away. They can be found in a variety of environments, from deserts to grasslands to forests. Inselbergs can provide important habitat for plants and animals that are adapted to the unique conditions found on these isolated formations.

Inset

An Inset is a smaller map or illustration that is included within a larger map or document to provide additional detail or context. Insets can be used to highlight a specific area within the larger map or to provide a close-up view of a particular feature or location. Insets can be used in a variety of maps, such as topographic maps, road maps, and nautical charts.  They can also be used in documents such as textbooks and scientific papers to provide additional information or visual aids.

Intensity-Duration-Frequency Curve

An Intensity-Duration-Frequency (IDF) Curve is a graphical representation of the relationship between rainfall intensity, duration, and frequency of occurrence. IDF curves are commonly used in hydrology to estimate the frequency and magnitude of floods in a given area.  The curves are typically generated using historical rainfall data and can be used to estimate the design rainfall for various engineering and planning applications.

Interfluve

An Interfluve is a ridge or high ground that separates two adjacent river valleys or watersheds. Interfluves can be composed of a variety of materials, including rock, soil, and vegetation.  They can be formed through a variety of processes, such as tectonic uplift, erosion, and sediment deposition. Interfluves can have important ecological functions, such as providing habitat for plant and animal species and regulating the flow of water and nutrients between adjacent watersheds.  They can also be important for human activities such as transportation and resource extraction.

Interior

The Interior is the central or inland part of a country or continent, typically characterized by lower elevations and less rugged terrain than the surrounding regions.  The interior can refer to any region that is not located on a coast or border. In many countries, the interior is home to large areas of agricultural land and natural resources, such as oil, gas, and minerals.

Intermittent Stream

An Intermittent Stream is a watercourse that flows only during certain times of the year, such as during and after rainstorms or snowmelt. Intermittent streams are typically located in areas with irregular precipitation patterns or in regions with dry or arid climates.  During dry periods, intermittent streams may be reduced to isolated pools or completely dry up.  These streams can still play an important ecological role by providing habitat for plants and animals that are adapted to the seasonal fluctuations in water availability.

International Date Line

The International Date Line is an imaginary line on the surface of the Earth that roughly follows the 180° longitude line.  The International Date Line is the point at which each new day begins, and it is the place where the calendar changes by one day.  Traveling west across the International Date Line results in a gain of one day, while traveling east across the line results in a loss of one day.

International Map

An International Map is a map that has been created to meet global standards and is recognized by international organizations such as the United Nations. International maps are typically designed to be used by a wide range of users, including government agencies, researchers, and the general public.  They often use standard symbols and conventions to represent geographic features, and may include multiple languages to be accessible to a global audience.  International maps can be used for a variety of purposes, including navigation, land use planning, and environmental management.

Intersection Point

An Intersection Point is a point where two or more lines or surfaces meet or cross each other.  In topography, an intersection point is commonly used to denote the point where two or more contour lines intersect, indicating a specific elevation or height.  Intersection points can also be used in surveying to determine the location of a specific point on a map or plan.

Intertidal Zone

The Intertidal Zone is the area of the shore or seafloor that is exposed to air at low tide and covered by seawater at high tide.  This zone is characterized by a variety of unique habitats and organisms that are adapted to survive the constant changes in water levels, temperature, and salinity.  The intertidal zone is an important ecological and economic resource, providing habitat for a variety of marine species and supporting activities such as fishing, tourism, and recreation.

Interval Line

An Interval Line is a line that represents a range of values or measurements within a larger dataset.  In cartography, interval lines are often used to represent topographic features, such as contour lines, that indicate changes in elevation or height.  Interval lines can also be used in other types of maps and graphs to represent different types of data, such as temperature, precipitation, or population density.

Intrusion

In geology, an Intrusion is a body of igneous rock that has been injected into surrounding rock formations.  Intrusions can take various shapes and forms, from small veins or dikes to large batholiths or laccoliths.  Intrusions can have a significant impact on the surrounding geology and can be associated with mineral deposits, such as gold or copper.  Intrusions can also be used to date the age of surrounding rock formations, providing important information about the geological history of an area.

Intrusive Rock

Intrusive rock, also known as plutonic rock, is a type of igneous rock that is formed when magma slowly cools and solidifies beneath the earth’s surface.  This slow cooling process allows large crystals to form, giving intrusive rock a coarse-grained texture.  Intrusive rocks can be found in a variety of forms, including dikes, sills, and batholiths.  These rocks are often associated with valuable mineral deposits and can be used in construction and as ornamental stone.

Inundation Map

An inundation map is a type of map that shows areas that are at risk of flooding during a storm surge, hurricane, or other extreme weather event.  These maps are used by emergency managers and planners to help identify areas that may need to be evacuated or fortified in the event of a major flood.  Inundation maps can be created using a variety of data sources, including topographic maps, hydrological models, and historical flood data.

Inverted Relief

Inverted relief is a type of map or image that shows topography in reverse, with depressions appearing as raised features and vice versa.  This type of map is often used in geology and mineral exploration to help identify buried structures, such as faults or ore bodies. Inverted relief maps can be created using a variety of techniques, including seismic reflection surveys, gravity surveys, and electromagnetic surveys.

Is

An is is a term used in cartography to denote a line of equal value or measurement.  For example, an isobar is a line on a weather map that connects points of equal atmospheric pressure.  Similarly, an isohyet is a line on a map that connects points of equal precipitation.  The term “is” is derived from the Greek word isos, meaning “equal.”

Isarithmic Map

An isarithmic map is a type of map that displays continuous data, such as temperature or elevation, using contour lines or color shading to show areas of equal value.  This type of map is commonly used in scientific and engineering applications, as it allows users to quickly and easily visualize spatial patterns and variations in data.

Isobar

An isobar is a line on a weather map that connects points of equal atmospheric pressure.  These lines are used to help forecast weather patterns, as areas of high and low pressure can have significant impacts on weather conditions. Isobars are typically labeled in millibars or inches of mercury, and are spaced at regular intervals on weather maps.

Isobaric Map

An isobaric map is a type of map that shows areas of equal atmospheric pressure at a specific altitude or height.  These maps are commonly used in aviation and meteorology to help predict weather patterns and to aid in flight planning. Isobaric maps can be created using a variety of data sources, including weather balloons, satellite imagery, and computer models.

Isobase

An isobase is a line on a map that connects points of equal depth or elevation below sea level.  These lines are commonly used in oceanography and geology to help visualize underwater topography and features, such as trenches and seamounts.  Isobases can also be used to show the depth of lakes and other bodies of water.

Isogonic Line

An isogonic line is a line on a map that connects points of equal magnetic declination, which is the angle between true north and magnetic north. These lines are used in navigation to correct for magnetic variations, as the angle between true north and magnetic north changes depending on the location on the Earth’s surface. Isogonic lines are typically labeled with the declination angle at a specific location.

Isogram

An isogram is a line on a map that connects points of equal value for a particular variable, such as temperature, precipitation, or elevation. Isograms are used to visualize patterns and variations in data and are commonly used in scientific research and engineering applications.

Isohyet

An isohyet is a line on a map that connects points of equal rainfall or precipitation.  These lines are used to create rainfall maps and to analyze precipitation patterns over a particular region. Isohyets are typically labeled with the amount of precipitation at a specific location.

Isoline

An isoline is a general term used to describe any line on a map that connects points of equal value for a particular variable, such as temperature, elevation, or pressure. Isolines are used to help visualize spatial patterns and variations in data and are commonly used in scientific research, engineering, and cartography. Examples of isolines include isobars, isohyets, isotherms, and contour lines.

Isopach

An isopach is a line on a map that connects points of equal thickness for a particular rock layer or sedimentary deposit.  Isopachs are commonly used in geology and oil exploration to map the distribution and thickness of underground rock layers.  Isopachs are typically labeled with the thickness of the rock layer at a specific location.

Isopachyte

An isopachyte is a contour line on a map that connects points of equal thickness for a particular rock layer or sedimentary deposit.  Isopachytes are similar to isopachs but are typically used in more detailed mapping and analysis.  Isopachytes are commonly used in geological mapping, oil and gas exploration, and mining.

Isopleth

An isopleth is a line on a map that connects points of equal value for a particular variable, such as temperature, pressure, or population density. Isopleths are used to visualize spatial patterns and variations in data and are commonly used in scientific research, cartography, and geography.

Isostasy

Isostasy is the state of balance or equilibrium between the Earth’s lithosphere and asthenosphere.  The lithosphere is the rigid outer layer of the Earth that includes the crust and uppermost part of the mantle, while the asthenosphere is a softer, more ductile layer beneath the lithosphere. Isostasy is the concept that the lithosphere “floats” on the asthenosphere, and changes in the thickness and density of the lithosphere can cause changes in the Earth’s surface elevation.

Isostatic Rebound

Isostatic rebound is the process by which the Earth’s surface rises after a heavy weight is removed, such as the melting of a glacier.  When a heavy weight, such as a glacier, is present, it depresses the Earth’s surface.  When the weight is removed, the lithosphere rebounds and rises back to its previous elevation. Isostatic rebound is a gradual process that can take thousands of years and can be measured using techniques such as GPS and satellite imagery.