Earth to Class

Core Concepts - Shaping the Earth's Surface

2.1p. Landforms are the result of the interaction of tectonic forces and the processes of weathering, erosion, and deposition.

2.1q. Topographic maps represent landforms through use of contour lines (isolines connecting points of equal elevation.) Gradients and profiles can be determined from changes in elevation over a given distance.

2.1r. Climate variations, structure, and characteristics of bedrock influence the development of landscape features including mountains, plateaus, plains, valleys, ridges, escarpments, and stream drainage patterns.

2.1s. Weathering is the physical and chemical breakdown of rocks at or near Earth's surface. Soils are the result of weathering and biological activity over long periods of time.

2.1t. Natural agents of erosion, generally driven by gravity, remove, transport, and deposit weathered rock particles. Each agent of erosion produces distinctive changes in the material that it transports, and creates characteristic surface features and landscapes. In certain erosional situations, loss of property, personal injury, and loss of life can be reduced by effective emergency preparedness.

2.1u. The natural agents of erosion include:

> Streams (running water): Gradient, discharge, and channel shape influence a stream's velocity and the erosion and deposition of sediments. Sediments transported by streams tend to become rounded as a result of abrasion. Stream features include V-shaped valleys, deltas, flood plains, and meanders. A watershed is the area drained by a stream and its tributaries.

> Glaciers (moving ice): Glacial erosional processes include the formation of U-shaped valleys, parallel scratches, and grooves in bedrock. Glacial features include moraines, drumlins, kettle lakes, finger lakes, and outwash plains.

>Wave Action: Erosion and deposition cause changes in shoreline features, including beaches, sandbars, and barrier islands. Wave action rounds sediments as a result of abrasion. Waves approaching a shoreline move sand parallel to the shore within the zone of breaking waves.

> Wind: Erosion of sediments by wind is most common in arid climates and along shorelines. Wind-generated features include dunes and sand-blasted bedrock.

> Mass Movement: Earth materials move downslope under the influence of gravity.

2.1v. Patterns of deposition result from a loss of energy within the transporting system, and are influenced by the size, shape, and density of the transported particles. Sediment deposits may be sorted or unsorted.

2.1w. Sediments of inorganic and organic origin often accumulate in depositional environments. Sedimentary rocks form when sediments are compacted and/or cemented after burial, or as the result of chemical precipitation from seawater.