Glaciers, Deserts and Wind Types of Glaciers A _________________ is a thick ice mass that forms above the ________________ over hundreds or thousands of years. The ______ ________ was a period of time when much of the Earth was covered in glaciers. Valley Glaciers Ice masses that slowly _______________ down mountain valleys originally occupied by streams. A stream of ice that flows between steep rock walls from near the top of the mountain valley. Ice Sheets / Continental Glaciers _____________________ are enormous ice masses that flow in all directions from one or more centers and cover everything but the highest land. Ice sheets are sometimes called ______________ ice sheets because they cover large regions where the climate is extremely ________. They are ________ compared to valley glaciers They currently cover __________________ and ____________________. How Glaciers Move The movement of glaciers is referred to as _______, and it happens in two ways. 1. Plastic flow— _____________________________________________ 2. Basal slip— _______________________________________________ Budget of a Glacier The glacial budget is the ______________, or lack of balance, between __________________ at the upper end of a glacier and loss, or ____________, at the lower end. Glacial Erosion Many landscapes were changed by the widespread glaciers of the recent ice age. How Glaciers Erode ● Plucking— ______________________ ● ____________ - Rock flour (pulverized rock) - __________________ (grooves in the bedrock) Landforms Created by Glacial Erosion Glaciers are responsible for a variety of _____________ landscape features, such as glacial troughs, ______________ valleys, __________, arêtes, and __________. Glaciated Valleys A _______________________ is a U-shaped valley that was once ________________ but was deepen by a glacier. A ____________ is a bowl-shaped depression at the head of a glacial valley. Arêtes and Horns • Snaking, ________-edged ridges called ___________ and sharp pyramidlike peaks called ________ project above mountain landscapes. Glacial Deposits Types of Glacial Drift Glacial drift applies to all sediments of glacial origin, no matter how, where, or in what form they were deposited. There are two types of glacial drift. 1. ________ is material deposited directly by the glacier. 2. ______________________ is sediment laid down by glacial meltwater. Moraines, Outwash Plains, and Kettles Glaciers are responsible for a variety of depositional features, including _____________________—layers or ridges of till - Lateral - Medial - Terminal end Glaciers are responsible for a variety of depositional features, including ___________________—sloping plains consisting of deposits from meltwater streams in front of the margin of an ice sheet ________________—depressions created when a block of ice becomes lodged in glacial deposits and subsequently melts ______________ —streamlined, asymmetrical hills composed of glacial dirt __________—ridges composed largely of sand and gravel deposited by a stream flowing beneath a glacier near its terminus Glaciers of the Ice age Ice Age Began ____ to ____ million years ago Division of geological time is called the ________________ epoch Ice covered _____% of Earth's land area. Greatly affected _________________ Many ice ages since from this time, including the last one approx. _______________ years ago. (Wisconsin Ice Sheet) Geologic Processes in Arid Climates Weathering Much of the weathered ____________ in deserts results from mechanical weathering. Chemical weathering is not completely _____________ in deserts. Over long time spans, clay and ______ soils do form. • Not as effective as in ___________ regions The Role of Water In the desert, most streams are _________________—they only carry water after it rains. Deserts Basin and Range: A Desert Landscape Most desert ______________ dry up long before they ever reach the ____________. The streams are quickly depleted by ________________ and soil infiltration. Interior drainage into basins produces _______________________—a fan-shaped deposit of sediment formed when a stream’s slope is abruptly reduced ______________________—a flat area on the floor of an undrained desert basin (playa) that fills and becomes a lake after heavy rain Most desert erosion results from _____________water. Although wind erosion is more ________________ in deserts than elsewhere, ____________ does most of the erosional work in deserts. Wind Erosion Wind erodes in the desert in two ways 1. _________________ is the lifting and removal of loose particles such as clay and silt. It produces blowouts _______________________—a layer of coarse pebbles and gravel created when wind removed the finer material Wind Deposits The wind can create _________________ when it deposits its sediments, especially in deserts and along ___________. Both layers of ________ and sand dunes are landscape features deposited by the ________. Loess Deposits of ________________ silt Extensive ______________deposits Primary sources are ______________ and glacial stratified drift. Sand Dunes Unlike deposits of loess, which form blanket-like layers over broad areas, winds commonly deposit sand in mounds or ridges called ___________. • Characteristic features - Slip face is the _____________slope of the dune - _____________________ are the sloping layers of sand in the dune. Types of Sand Dunes • 1. 2. 3. 4. 5. 6. What form sand dunes assume depends on the wind direction and speed, how much sand is available, and the amount of vegetation.