Earthquake

Earthquake is a geological event that occurs due to the sudden release of energy within the earth’s crust.  It often results in seismic waves that cause shaking and ground deformation.  The strength of an earthquake is measured on the Richter scale, which assigns a magnitude value to the event. Earthquakes can be caused by natural processes such as tectonic plate movements or volcanic eruptions, as well as human activities like underground mining or the construction of large dams.

Easting

Easting is a term used in cartography and surveying to describe the horizontal location of a point on a map or survey.  It is usually measured in meters or feet and represents the distance of the point from the east-west reference line or meridian.

Echelon

Echelon refers to a formation of objects or features arranged in a staggered pattern.  In topography, echelon can refer to the arrangement of hills or mountains in a row, with each peak slightly offset from the next.  This can occur due to tectonic processes or erosion patterns.

Ecotone

Ecotone is a transitional zone where two different ecosystems meet and blend. It is a boundary area where the characteristics of the two ecosystems overlap and create a unique environment.  For example, the ecotone between a forest and a grassland may have characteristics of both, with some trees and shrubs growing alongside grasses and wildflowers.  The ecotone is an important area for biodiversity as it provides habitats for many species that require both ecosystems to survive.

Edge-matching

Edge-matching is a technique used in cartography to ensure that adjacent maps fit together seamlessly.  It involves aligning the edges of maps and ensuring that geographic features are properly matched across the boundary lines.  This technique is important for creating large-scale maps and atlases, where multiple sheets are required to cover a large area.

Edifices

Edifices refer to large, impressive buildings or structures. In geology, edifices refer to the physical formations created by volcanic activity, such as cones, calderas, and lava domes.  These edifices are often steep-sided and made of solidified magma and ash.

Eight-point Rose

The eight-point rose is a compass rose with eight directional points, rather than the four points on a traditional compass.  The eight points are the cardinal points (north, south, east, and west) and the intercardinal points (northeast, southeast, southwest, and northwest).  This type of compass rose is commonly used in navigation and mapping, particularly for marine and aviation purposes.

Electromagnetic Survey

Electromagnetic survey is a geophysical technique used to map the subsurface features of the earth by measuring variations in electromagnetic fields. This method involves transmitting an electromagnetic signal into the ground and recording the response of the subsurface materials.  Electromagnetic surveys are used to identify geological features such as mineral deposits, groundwater resources, and hydrocarbon reserves.  This technique is particularly useful in areas where other methods of exploration, such as drilling or excavation, are difficult or expensive to perform.

Elevation

Elevation refers to the height of a point or object above a reference point, such as sea level.  It is an important concept in cartography, surveying, and geography.  Elevation can be represented on maps using contour lines or shading, which indicate changes in elevation.  Elevation is often used in conjunction with other topographical features, such as slopes and drainage patterns, to create a comprehensive understanding of the terrain.

Elevation Diagram

An elevation diagram is a type of diagram that represents changes in elevation along a given path or section.  These diagrams are commonly used in engineering and construction to help visualize the terrain along a proposed roadway, pipeline, or other linear feature.  Elevation diagrams typically show the vertical scale of the terrain, as well as any man-made structures or topographical features that may affect the elevation of the ground.

Elevation Interval

Elevation interval refers to the vertical distance between two adjacent contour lines on a map or elevation diagram.  It is also known as the contour interval and is typically expressed in feet or meters.  Elevation intervals are important because they determine the level of detail shown on a map or diagram.  A smaller elevation interval indicates a more detailed representation of the terrain, while a larger interval may result in a more generalized view.

Elevation Map

An elevation map, also known as a topographic map, is a type of map that displays the elevations of land features such as mountains, hills, valleys, and plateaus.  The elevations are usually measured relative to sea level and are represented by contour lines on the map.  These contour lines connect points of equal elevation, forming a detailed picture of the land’s surface.  Elevation maps are widely used in a variety of applications, from outdoor activities like hiking and skiing to scientific research in fields such as geology and hydrology.  They can also be used to identify potential flood zones, plan infrastructure projects, and locate natural resources such as minerals and water. In addition, elevation maps can be combined with other types of maps to provide a more complete picture of an area, such as a topographic map combined with a satellite image to show land cover and vegetation.

Elevation Point

Elevation point is a point on the earth’s surface with a specific elevation, which is the vertical distance above or below a reference datum.  Elevation is an important measurement for topographical mapping and surveying.  An elevation point can be determined using various methods such as GPS, total station, or leveling.  The elevation of a point can also be represented on a map using contour lines or shading.

Embankment

An embankment is a man-made structure used to raise the elevation of the ground surface.  It is commonly used to create roads, railways, and canals. The height and volume of an embankment can be determined by surveying the elevation of the natural ground surface and the required height of the structure.  Embankment volume is the total amount of material required to build the embankment and is calculated by multiplying the area of the cross-section of the embankment by its length.

Embankment Volume

Embankment volume is the amount of material used to construct an embankment, such as a roadway or levee.  It is calculated by multiplying the cross-sectional area of the embankment by its length.

End Moraine

End moraine is a type of moraine that is formed at the terminus of a glacier.  It is created when the glacier deposits rocks, soil, and other debris at its front edge.  End moraines can form ridges, hills, or mounds, and are often used as indicators of past glacial activity.

Equator

The Equator is an imaginary line that circles the Earth and lies halfway between the North and South Poles.  It divides the Earth into the Northern and Southern Hemispheres.  The Equator is the widest part of the Earth, and it is approximately 40,075 kilometers long.  The temperature near the Equator is generally warm due to the direct sunlight that it receives.  The Equator is also important for navigation and cartography purposes.

Erosion

Erosion is the process by which soil and rock are removed from the Earth’s surface by natural agents such as water, wind, ice, and gravity.  The process of erosion can be very slow or very rapid, depending on the strength of the agents causing the erosion and the resistance of the soil or rock being eroded.  Erosion can cause landforms such as canyons, valleys, and cliffs.

Erratic

An erratic is a large boulder or rock that is different from the surrounding rock and was likely transported by glacial ice from its place of origin.  Erratics are often found far from their original location and can be used to help determine the direction and extent of glacial movement.  Erratics can range in size from small stones to massive boulders weighing thousands of tons.

Equal Interval

Equal interval is a method of creating map contours in which the difference in elevation between each contour line is the same.  For example, if a map has contour lines at 50-meter intervals, each line represents an increase or decrease of 50 meters in elevation.  This method is commonly used to create topographic maps and provides a clear visualization of the terrain.

Escarpment

Escarpment refers to a steep slope or long cliff that separates two flat or gently sloping areas of land.  These geological features are formed by erosion, tectonic activity or a combination of both. Escarpments can be found in various landscapes such as mountains, plateaus, and coastal areas. They are often formed by the differential erosion of the hard and soft rocks, resulting in a steep slope or cliff-like structure.

Esker

Esker is a type of long and narrow ridge of sand, gravel or clay that is formed by a stream flowing through a glacier.  As the glacier melts, the sediments deposited by the stream form a ridge, which is typically several meters high and several kilometers long.  Eskers are common in areas that have experienced glaciation, such as Canada, northern Europe, and the northern United States.

Estuary

Estuary refers to the area where a river meets the sea, and saltwater and freshwater mix.  Estuaries are typically characterized by brackish water, which is a mix of freshwater and saltwater.  They are home to a diverse range of plant and animal species, including fish, birds, and marine mammals. Estuaries also play an important role in the economy, as they provide a habitat for commercial and recreational fishing, as well as shipping routes.

Evapotranspiration

Evapotranspiration is the process by which water is transferred from the land to the atmosphere.  It is a combination of two processes: evaporation and transpiration.  Evaporation refers to the process by which water changes from a liquid to a gas, while transpiration refers to the release of water vapor from plants. Together, these processes account for the majority of water loss from the Earth’s surface.  Evapotranspiration is an important part of the water cycle and has implications for both weather and climate.

Exfoliation

Exfoliation is a geological process where rock layers peel off due to weathering or pressure changes.  This can occur due to heating and cooling cycles or the removal of overlying layers. When exposed to high temperatures, rocks may expand and contract, causing surface layers to crack and flake off. Over time, this can lead to the development of curved surfaces or boulder-sized formations that look like they are peeling away from the rock face.

Expansive Soil

Expansive soil is a type of soil that has the potential to expand and contract significantly in response to moisture content changes.  These soils can be found in arid and semi-arid regions and are made up of clay minerals that absorb water when available and release it when conditions are dry.  This expansion and contraction can lead to soil movement and foundation damage in buildings constructed on top of these soils.

Exploration Survey

Exploration survey is a type of survey that is conducted to determine the location, nature, and extent of minerals, natural resources, or archaeological features in an area.  This type of survey involves the use of various tools, including aerial photography, ground-based sensors, and geophysical equipment.  The data collected during exploration surveys can help to inform decisions related to land use, resource extraction, or conservation efforts.

Extent

Extent refers to the spatial scope or geographic coverage of a feature or phenomenon.  This term can be used in a variety of contexts, such as describing the range of a plant species, the extent of a flood zone, or the extent of an archaeological site.  The extent of a feature can be measured in various units, such as distance, area, or volume, depending on the nature of the feature and the purpose of the analysis.

Extrapolation

Extrapolation is a statistical method of predicting future values based on past observations or data.  This method involves extending the trend line of a data set beyond the range of the observed data to make predictions about future values.  Extrapolation is commonly used in many fields, including economics, finance, and environmental science.  In environmental science, extrapolation is often used to make predictions about the future state of the environment based on current data.  For example, scientists might use data on current levels of greenhouse gases to extrapolate and predict future climate change patterns.

Eye-level Photography

Eye-level photography is a technique used in photography where the camera is positioned at the height of the photographer’s eyes. This technique is often used in landscape photography to capture images that resemble the natural perspective of human vision.  Eye-level photography can also be used to create a sense of intimacy and connection with the subject, especially in portrait photography.  Eye-level photography can be contrasted with aerial photography, which is taken from an elevated position above the ground, and ground-level photography, which is taken from a low position on the ground. Each of these techniques has its own unique advantages and disadvantages, and the choice of technique often depends on the desired outcome of the photograph.