Glaciers Glaciers are a part of both the hydrologic cycle and rock cycle Glacier a thick mass of ice that forms over land from the compaction and recrystallization of snow and shows evidence of past or present flow Glaciers Types of glaciers
Valley, or alpine glaciers form in mountainous areas Kennicott Glacier Glaciers Types of glaciers Ice sheets or continental glaciers
Large scale e.g., Over Greenland and Antarctica Other types Ice caps and piedmont glaciers Glacier Movement Types of glacial movements Zone of fracture
Plastic flow Slipping along the ground Zone of fracture Uppermost 50 meters Crevasses form in brittle ice Crevasses Glacier Movement Zone of accumulation the area where a glacier forms
Zone of wastage the area where there is a net loss due to melting Glacial Erosion Glaciers erode by Plucking lifting of rock blocks
Abrasion Rock flour (pulverized rock) Striations (grooves in the bedrock) Glacial Erosion Landforms created by glacial erosion Glacial trough
Hanging valley Cirque Arte Horn Fiord Erosional Landforms Created by Alpine Glaciers The Matterhorn in the Swiss Alps Glacial Deposits Glacial drift All sediments of glacial origin
Types of glacial drift Till material that is deposited directly by ice Stratified drift sediment deposited by meltwater Glacial Deposits Depositional features
Moraines layers or ridges of till Types of moraines Lateral Medial End Ground End Moraines of the Great Lakes Region Glacial Deposits Depositional features Outwash plain or valley train
Kettles Drumlins Eskers Kames Glacial Depositional Features Ice Age Glaciers Glaciers of the past Ice Age
Began 2 to 3 million years ago Division of geological time is called the Pleistocene epoch Ice covered 30 percent of Earths land area Extent of Ice Age Glaciation Ice Age Glaciers Effects of Ice Age glaciers
Migration of animals and plants Rebounding upward of the crust Worldwide change in sea level Climatic changes Ice Age Sea Level Causes of Ice Ages Successful theory must account for
Cooling of Earth, as well as Short-term climatic changes Proposed possible causes Plate tectonics Continents were arranged differently Changes in oceanic circulation Late Paleozoic Ice Age Causes of Ice Ages Variations in Earths orbit Milankovitch hypothesis
Shape (eccentricity) of Earths orbit varies Angle of Earths axis (obliquity) changes Axis wobbles (precession) Changes in climate over the past several hundred thousand years are closely associated with variations in Earths orbit Orbital Variations Deserts Any situation with a water deficiency
Distribution and causes of dry lands Global distribution of air pressure and winds Deep interiors of landmasses Presence of high mountains Global Dry Climate Distribution Deserts Geologic processes in arid climates Weathering
Not as effective as in humid regions Mechanical weathering forms unaltered rock and mineral fragments Some chemical weathering does occur Clay forms Thin soil forms Deserts Geologic processes in arid climates
Role of water in arid climates Streams are dry most of the time Desert streams are said to be ephemeral Flow only during periods of rainfall Different names are used for desert streams including wash, arroyo, wadi, donga, and nullah Deserts Geologic processes in arid climates
Role of water in arid climates Desert rainfall Rain often occurs as heavy showers Causes flash floods Poorly integrated drainage Most erosional work in a desert is done by running water Desert Stream Channel Deserts Basin and range: the evolution of a desert landscape
Uplifted crustal blocks Interior drainage into basins produces Alluvial fans and bajadas Playas and playa lakes Deserts Basin and range: the evolution of a desert landscape
Erosion of mountain mass causes local relief to continually diminish Eventually mountains are reduced to a few large bedrock knobs called inselbergs projecting above a sediment-filled basin Landscape Evolution in a Basin and Range Region Deserts Wind erosion Deflation Abrasion Lifting of loose material
Produces Blowouts Desert pavement Abrasion Formation of Desert Pavement Deserts Types of wind deposits Loess Deposits of windblown silt
Extensive blanket deposits Primary sources are deserts and glacial stratified drift Deserts Types of wind deposits Sand dunes
Mounds and ridges of sand formed from the winds bed load Characteristic features Slip face the leeward slope of the dune Cross beds sloping layers of sand in the dune Formation of Sand Dunes Deserts Types of wind deposits Sand dunes Types of sand dunes
Barchan dunes Transverse dunes Longitudinal dunes Parabolic dunes Star dunes Sand Dune Types