glaciers and glaciation - exam 2 Flashcards
what forms from the accumulation, compaction, and recrystallization of snow?
glaciers
dynamic erosional agents that accumulate, transport, and deposit sediment
glaciers
glaciers that move slowly and follow the path of valleys originally occupied by streams are called
valley or alpine glaciers
when a glacier or ice sheet flows into the ocean, it is called a
tidewater glacier
where an advancing tidewater glacier reaches deeper water, the ice will float forming
an ice shelf
a type of glacier that completely buries the underlying landscape, but much smaller than ice sheets
ice caps
often ice caps and ice sheets feed
outlet glaciers
glaciers occupying broad lowlands at the bases of steep mountains and form when one or more alpine glaciers emerge from the confining walls of mountain valleys
piedmont glaciers
the type of glacial movement which involves movement within the ice
plastic flow
the type of glacial movement where the entire ice mass slips along the ground
basal slip
most glaciers are thought to move by the sliding process of
basal slip
movement of some glaciers is characterized by occasional periods of extremely rapid advances called
glacial surges
snow accumulation and ice formation occur in the
zone of accumulation
the elevation at which the accumulation and wasting of glacial ice are equal
snowline or equilibrium line
below the snowline is the
zone of wastage
the area where there is a net loss to the glacier as all the snow from the previous winter is melting as is the glacial ice
zone of wastage
the term for loss of ice by a glacier
ablation
the process where glaciers waste away as large pieces of ice break off the front of the glacier
calving
what can create icebergs in places where the glacier has reached the sea or a lake?
calving
the balance or lack of balance between accumulation at the upper end of the glacier and ablation at the lower end
the glacial budget
the process where a glacier flows over a fractured bedrock surface and losses and lifts blocks of rocks and incorporates them into the ice
plucking
this process occurs when meltwater penetrates the cracks and joints of bedrock beneath a glacier and freezes
plucking
the process where ice and rock fragments advance over bedrock and function as sandpaper, smoothing and polishing the surface below
abrasion
the pulverized rock produced by glacial abrasion is called
rock flour
when the ice at the bottom of a glacier contains large rock fragments and long scratches and grooves, what may be gouged into the bedrock?
glacial striations
valleys of tributary glaciers left standing above the main glacial trough are termed
hanging valleys
depressions in bedrock created by plucking and abrasion filled with water
pater noster lakes
the focal point of a glaciers growth because its the area of snow accumulation and ice formation
the cirque
what begins as irregularities in the mountainside that are enlarged by frost wedging and plucking along the sides and bottom of the glacier
a cirque
after a glacier has melted away, the cirque basin is sometimes occupied by a small lake called a
tarn
as glacial ice melts and drops its load of rock fragments, what is deposited?
till
boulders found in the till or lying free on the surface of the face
glacial erratics if different from the bedrock below
what is sorted according to the size and weight of the particles?
stratified drift
a widespread feature of glacial deposition of layers or ridges of till
moraine
alpine glaciers produce what two types of moraines?
lateral and medial moraines
what is created when two alpine glaciers coalesce to form a single ice stream?
medial moraine
a ridge of till that forms at the terminus of a glacier
end moraine
a gently rolling layer of till deposited as the ice front recedes is termed a
ground moraine
in areas that were once covered by continual ice sheets, there is a variety of glacial landscape characterized by smooth, elongate, and parallel hills called
drumlins
the sediment acquired and transported by a glacier that is ultimately deposited by streams of glacial meltwater flowing, on, within, beneath, and beyond a glacier is called
stratifed drift
most of the major glacial stages occurred during a division of the geologic time scale called the
quaternary period
earlier glaciations are indicated by deposits of
tillite
a sedimentary rock formed when glacial till becomes lithified
tillite
