Habitat

Habitat refers to a specific natural environment that is home to particular flora and fauna.  It can be defined by physical features such as climate, topography, and soil type. A habitat can range from a small area like a pond to vast expanses like a rainforest.  The types of organisms found in a habitat are adapted to its specific conditions.

Hachure

Hachure is a topographical symbol used to represent slopes or depressions on a map.  It is a series of short lines drawn perpendicular to the contour line, indicating the steepness of the slope or the depth of the depression.  The closer the hachure lines are to each other, the steeper the slope or deeper the depression.

Hand Level

Hand level is a simple tool used to determine the slope of the land. It consists of a small level mounted on a handheld device, typically a stick or a ruler. By holding the device against the ground and adjusting the level, the user can determine the angle of the slope.

Hanging Valley

Hanging valley is a geological feature found in mountainous areas.  It is formed when a small tributary glacier meets a larger glacier, and the smaller glacier is unable to erode the valley floor to the same depth as the larger glacier.  As a result, the smaller glacier hangs above the main valley, creating a distinctive U-shaped valley with a steep drop-off at the end. Hanging valleys are often marked by waterfalls where the smaller glacier’s meltwater cascades down into the main valley.

Hanging Wall

Hanging wall is a term used in geology to describe the block of rock that lies above a dipping fault plane.  This block of rock is called the “hanging wall” because it hangs over the fault plane.  The hanging wall moves down relative to the footwall during faulting, which can cause earthquakes and other geological phenomena.  The angle at which the fault plane dips, determines the geometry of the hanging wall and the footwall.

Hardpan

Hardpan is a layer of dense soil or rock that forms beneath the topsoil.  It can be impermeable to water and roots, which can make it difficult for plants to grow.  Hardpan can form naturally due to geological processes or can be created by human activities like overgrazing or construction.  It is often found in arid regions and can be a significant obstacle for agriculture.

Hatch

Hatch is a term used to describe a narrow opening in a wall or ceiling, typically used for ventilation or access. t can be found in a variety of settings, including buildings, ships, and submarines.  Hatches can be simple or complex, and they may have locking mechanisms to control access. In some cases, hatches may also be used for emergency escape.

Hazard Map

Hazard map is a type of map that shows areas that are at risk from natural disasters or other hazards.  It is used to inform people about the potential risks in a given area and to help them make informed decisions about where to live or build structures.  Hazard maps can show areas at risk from floods, earthquakes, wildfires, and other hazards.  They are often used by emergency planners and policymakers to help reduce the risk of disasters and to develop evacuation plans.

Headland

A headland is a narrow piece of land that juts out into the sea, forming a distinct and often prominent feature of a coastline.  They are typically composed of resistant rock, such as granite or basalt, which is more resistant to erosion than the surrounding coastline.  Headlands often have steep cliffs on one or more sides and can be popular sites for hiking, fishing, and other outdoor activities.

Headwall

A headwall is a steep rock face at the head of a valley or canyon.  It is typically formed by erosion from a stream or glacier that has cut into the rock over time. Headwalls can be dangerous for climbers and hikers, as loose rock and unstable slopes can cause rockfall and avalanches.

Height of Burst

The height of burst is the altitude at which a nuclear explosion occurs above the ground.  It is a crucial factor in determining the effects of a nuclear weapon, as it can affect the size and shape of the blast wave, the amount of heat and radiation released, and the level of damage to structures and infrastructure.  The height of burst is typically measured in feet or meters above ground level.

Helicopter Survey

A helicopter survey is a method of gathering data about the topography and geology of an area using a helicopter equipped with specialized equipment such as LiDAR or aerial cameras.  Helicopter surveys are often used in areas that are difficult to access by other means, such as remote mountain ranges or densely forested areas.  They can provide highly detailed and accurate data about the terrain, which can be used for geological mapping, resource exploration, and environmental monitoring.  Helicopter surveys can also be used for search and rescue operations, as they can quickly cover large areas of terrain and provide a bird’s-eye view of the landscape.

Hemisphere

A hemisphere is a half of a sphere, which is a three-dimensional shape with a round surface.  Hemispheres can be found in various contexts, such as in geography where the Earth is divided into the Northern Hemisphere and Southern Hemisphere.  The Equator divides the Earth into two hemispheres, and each hemisphere has different climates and seasons. Hemispheres can also be used in other sciences, such as anatomy, where the brain is divided into two hemispheres, the left and right.

Hertzian Contact Stress

Hertzian contact stress is the stress that occurs when two objects come into contact with each other.  It is named after the German physicist Heinrich Rudolf Hertz, who studied the phenomenon in the 19th century.  Hertzian contact stress is most commonly encountered in mechanical engineering, where it is used to calculate the stresses that occur in gears, bearings, and other mechanical components. It can also be used to study the deformation and fracture of materials.

Hill

A hill is a raised area of land that is smaller than a mountain but larger than a mound or a hillside.  Hills can be found in a variety of landscapes, such as rolling hills in agricultural regions or rocky hills in mountainous areas.  They can be formed by various geological processes, such as erosion, tectonic activity, or volcanic activity. Hills can provide scenic views and recreational opportunities such as hiking, skiing, or mountain biking.

Hillshade

Hillshade is a technique used in cartography to create a shaded relief map of a landscape.  It uses the angle and direction of the sun’s rays to simulate the shadows that would be cast by hills and valleys in the terrain.  Hillshade maps can be used to visualize the topography of an area and to highlight the features of the landscape.  They are often used in geographic information systems (GIS) and in planning and management of natural resources.

Hinge Line

A hinge line is a line of folding or bending in a geological formation where the rock strata have been subjected to intense pressure or deformation. It is often found in mountain ranges where tectonic forces have caused the rocks to buckle and fold.  The hinge line is the line of maximum curvature in the fold and can be used to determine the orientation and shape of the fold. Hinge lines can be important in the exploration and production of oil and gas, as they can help geologists locate areas where the rock strata may have been folded or faulted, creating traps for hydrocarbons.

Historic Site

A historic site is a place or structure that has been designated as having cultural or historical significance.  Historic sites can range from archaeological sites that date back thousands of years to buildings that are only a few decades old.  They may be protected by law or managed by government agencies, non-profit organizations, or private individuals.  Historic sites can provide valuable information about the history and culture of a region, and they can be important for education, research, and tourism.

Holocene

The Holocene is the geological epoch that began around 11,700 years ago and continues to the present day.  It is characterized by the warming of the Earth’s climate following the last Ice Age, the development of agriculture and human civilization, and the rise of modern ecosystems.  The Holocene is named for its characteristic deposits of peat, which were formed during the warm and wet conditions of the epoch.

Horizon

A horizon is a layer of soil or rock that is distinguishable from the layers above and below it.  Horizons can be used to study the formation and properties of soils and to identify different types of rock formations.  The A horizon, or topsoil, is the layer where most organic matter is found and where plants grow.  The B horizon, or subsoil, is a layer of partially weathered rock and mineral material that can provide clues about the geological history of the area.  The C horizon, or parent material, is the layer of unweathered rock or sediment that underlies the soil.

Horn

A horn is a pointed mountain peak that is created by the erosion of glaciers on multiple sides of a mountain.  Horns are often found in alpine regions and are characterized by their steep, jagged ridges and narrow summits.  They can pose a challenge for climbers due to their difficult and often exposed terrain.

Horseshoe Bend

A horseshoe bend is a U-shaped bend or meander in a river or stream that resembles the shape of a horseshoe.  Horseshoe bends are formed by the lateral erosion of the outer bank of a meandering river, which creates a loop or bend that gradually widens and deepens over time.  They are common in rivers with low gradient and are often considered scenic features.

Hot Spot

A hot spot is a region of the Earth’s mantle where molten rock, or magma, rises to the surface and creates volcanic activity.  Hot spots are thought to be caused by plumes of hot material that rise from deep within the Earth’s mantle.  They can occur both on land, such as the Hawaiian Islands, and in the ocean, such as the Mid-Atlantic Ridge.

Hydraulic Gradient

The hydraulic gradient is the slope or steepness of a groundwater table, or the rate at which water flows through a soil or rock formation.  It is a measure of the difference in water pressure between two points in a groundwater system and is determined by the elevation, or head, of the water table at each point.  The hydraulic gradient is an important factor in the movement of water through soils and rocks, and can affect the rate of groundwater recharge and discharge, as well as the quality of groundwater resources.

Hydrographic Survey

Hydrographic survey is the process of mapping and measuring the physical features of bodies of water, such as oceans, lakes, and rivers.  The main objective of hydrographic surveying is to collect accurate data on the depth, shape, and nature of the water bodies, which is then used to produce navigational charts and maps.

Hydrography

Hydrography is the science of measuring and mapping the physical features of water bodies, including their depth, shape, and composition.  It includes the study of the movement and distribution of water in the Earth’s surface and subsurface, as well as the physical and chemical properties of water.

Hydrology

Hydrology is the scientific study of water in the Earth’s surface and subsurface, including its distribution, movement, and properties.  Hydrology deals with the processes that govern the movement of water through the hydrological cycle, which includes precipitation, infiltration, evaporation, and runoff.

Hypsometric Tinting

Hypsometric tinting is a cartographic technique that involves the use of colors to represent elevation or topographic relief on a map.  The technique uses a range of colors to represent different elevation levels, with darker colors representing higher elevations and lighter colors representing lower elevations.

Hypsometry

Hypsometry is the study of the distribution of elevations on the Earth’s surface. It is used to determine the proportion of land area at different elevations and to create hypsometric curves, which represent the frequency distribution of elevations in a given area.  Hypsometry is an important tool for understanding the topography of the Earth’s surface and for analyzing the distribution of water resources.