[Regents Prep Earth Science] Weathering, Erosion, Deposition, & Landforms: Landforms

Landscape Characteristics
Earth’s landscapes are the results of the interaction of crustal materials, forces, climate, human activities, and time.

Landscape Regions
Landscape regions can usually be identified by the elevation of the region. Mountains, plateaus, and plains identify landscape regions. Mountains have high elevation and deformed rock structures due to the great forces that occur when mountains are forming. Plateaus have medium to high elevation. Plains are low in elevation and usually have horizontal rock layers. The boundaries between these 3 distinct areas are generally well defined. Landscape regions tend to be separated by mountains, large bodies of water, and other natural boundaries. The image below is from page 2 of the Earth Science Reference Tables and explains where the three different landscape regions can be found in New York State.

Landscape Formation
The two major forces that oppose each other in the formation of landscapes are the forces of uplifting and erosion, also referred to as constructive and deconstructive forces. The uplifting process is constructive and includes natural occurrences such as: folding and faulting, earthquakes, volcanoes. This leads to erosion, which is part of the forces of deconstruction.

Climate also plays a large role in the formation of landscapes. Depending on location areas that are dry (arid) have very little vegetation present with large canyons. An area that is humid will get moderate to high amounts of precipitation. This leads to large amounts of vegetation and well-defined soil profiles. Humid areas are also known for their rounded hills.

Bedrock effects how the landscape looks according to its resistance to weathering and erosion. Stream drainage patterns are influenced by the rock beneath them. There are 4 main types of stream drainage patterns. They are known as DART: Dendritic, Annular, Radial, and Trellis:

Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. What makes glaciers unique is their ability to move. Due to sheer mass, glaciers flow like very slow rivers. Some glaciers are as small as football fields (Valley or Alpine), while others grow to be over a hundred kilometers long (Ice sheet).

Since the mid-nineteenth century, scientists and naturalists have closely studied glaciers. In this photograph from 1894, two men approach a yawning crevasse. For safety, they use rope harnesses, attaching themselves to more stable ground further away from the crevasse. Even today, people doing fieldwork on glaciers take these precautions. (H.F. Reid Collection at the World Data Center for Glaciology, Boulder)

Presently, glaciers occupy about 10 percent of the world's total land area, with most located in polar regions like Antarctica and Greenland. Glaciers can be thought as remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. An Ice Age occurs when cool temperatures endure for extended periods of time, allowing polar ice to advance into lower latitudes. For example, during the last Ice Age which ended about 11,000 year ago, giant glacial ice sheets extended from the poles to cover most of Canada, all of New England, much of the upper Midwest, large areas of Alaska, most of Greenland, Iceland, much of Great Britain and Ireland, and the northwestern part of the former Soviet Union.

Within the past 750,000 years, scientists know that there have been eight Ice Age cycles, separated by warmer periods called interglacial periods. Currently, the Earth is nearing the end of an interglacial, meaning that another Ice Age is due in a few thousand years. This is part of the normal climate variation cycle. Greenhouse warming may delay the onset of another glacial era, but scientists still have many questions to answer about climate change. Although glaciers change very slowly over long periods, they may provide important global climate change signals. (Referenced from: http://nsidc.org/glaciers)

Glacial deposition has literally carved out landscape regions around the world and in New York State. As glaciers move over the land they act as a "bulldozer" changing the view of the landscape. As glaciers pass over the land they leave distinct features that are very common to New York State. Since New York State was once cover by ice miles thick it is very easy to find the features in the image below somewhere near your school.