The one shown in Figure Drumlins made up of glacial sediments are very common in some areas of continental glaciation Figure On a smaller scale still, glacial grooves tens of centimetres to metres wide and glacial striae millimetres to centimetres wide are created by fragments of rock embedded in the ice at the base of a glacier Figure Glacial striae are very common on rock surfaces eroded by both alpine and continental glaciers. Lakes are common features in glacial environments.
A lake that is confined to a glacial cirque is known as a tarn Figure Tarns are common in areas of alpine glaciation because the ice that forms a cirque typically carves out a depression in bedrock that then fills with water. In some cases, a series of such basins will form, and the resulting lakes are called rock basin lakes or paternoster lakes. A lake that occupies a glacial valley, but is not confined to a cirque, is known as a finger lake. In some cases, a finger lake is confined by a dam formed by an end moraine, in which case it may be called a moraine lake Figure In areas of continental glaciation, the crust is depressed by the weight of glacial ice that is up to 4, m thick.
Basins are formed along the edges of continental glaciers except for those that cover entire continents like Antarctica and Greenland , and these basins fill with glacial meltwater.
Many such lakes, some of them huge, existed at various times along the southern edge of the Laurentide Ice Sheet. During the latter part of the last glaciation 30 ka to 15 ka , the ice holding back Lake Missoula retreated enough to allow some of the lake water to start flowing out, which escalated into a massive and rapid outflow over days to weeks during which much of the volume of the lake drained along the valley of the Columbia River to the Pacific Ocean.
The record of these massive floods is preserved in the Channelled Scablands of Idaho, Washington, and Oregon Figure If during a year, a glacier accumulates more ice than melts away, the glacier advances downhill.
If a glacier melts more than it accumulates over a year, it is retreating Figure below. Skip to main content. Search for:.
Glacial Erosion and Deposition Lesson Objectives Discuss the different erosional features formed by alpine glaciers. Describe the processes by which glaciers change the underlying rocks. Discuss the particles deposited by glaciers as they advance and recede.
Describe the landforms created by glacial deposits. Formation and Movement of Glaciers Glaciers are solid ice that move extremely slowly along the land surface Figure below.
The two types of glaciers are: Continental glaciers are large ice sheets that cover relatively flat ground. These glaciers flow outward from where the greatest amount of snow and ice accumulate.
Alpine or valley glaciers flow downhill through mountains along existing valleys. A satellite image of glaciers in the Himalaya with some features labeled. Glacial striations point the direction a glacier has gone. A U shaped valley in Glacier National Park. Yosemite Valley is known for waterfalls that plunge from hanging valleys.
Earth Science and Its Branches. Earth Science Glossary. Earth's Moon. Effects of Air Pollution. Energy in the Atmosphere.
Erosion and Deposition by Flowing Water. Erosion and Deposition by Glaciers. Erosion and Deposition by Gravity. Erosion and Deposition by Waves. Erosion and Deposition by Wind. Essential Questions. Formation of Minerals. Guiding Principles.
Humans and the Water Supply. Identification of Minerals. Igneous Landforms and Geothermal Activity. Igneous Rocks. Inner Planets. Inside Earth. Introduction to Earth's Surface. Introduction to the Oceans. Introduction to the Solar System. Layers of the Atmosphere. Loss of Soil. Measuring and Predicting Earthquakes. Mining and Using Minerals. Modeling Earth's Surface. Nature of Earthquakes. Nonrenewable Energy Resources. Ocean Life. Ocean Movements. Other Objects in the Solar System.
Outer Planets. Planet Earth. Pollution of the Land. Protecting the Water Supply. Raw Data. Recent Space Exploration. Reducing Air Pollution. Relative Ages of Rocks. Renewable Energy Resources.
Seafloor Spreading. Sedimentary Rocks. Staying Safe in Earthquakes. Stress in Earth's Crust. Surface Water. The Atmosphere. The Human Population. The Nature of Science. The Ocean Floor. The Origin of Earth. The Sun. The Sun and the Earth-Moon System. The Universe. Theory of Plate Tectonics. Topographic Maps. Types of Rocks. Types of Volcanoes. Use and Conservation of Energy. Use and Conservation of Resources. Using Satellites and Computers. Volcanic Activity. Volcanic Eruptions. Water on Earth.
Water Pollution. Weather and Water in the Atmosphere. Weather Forecasting. World Climates. Lesson Objectives Describe how continental and valley glaciers form. Explain how glaciers cause erosion. Identify landforms deposited by glaciers.
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