geo exam 3

what is a glacier

large, persistent body of dense ice

two types of glaciers

continental cover extremely large areas of land, alpine glaciers develop in high mountains and flow down valleys

how do glaciers form

gradual accumulation, compaction, and recrystallization of snow over many years

what is the snow line

boundary between snow covered surface and snow free surface

accumulation zone

upper part of a glacier where snow and ice build up

ablation zone

lower part of a glacier where ice is lost through melting and other processes

What happens when the rate of ablation is greater than the rate of accumulation?

the glacier retreats/melts

the formation of end moraines occurs when

a glacier is stationary

ground moraines are formed when

a glacier is retreating

what is moraine

pile of rocks, sediment, and debris that a glacier leaves behind as it moves or melts

lateral moraine

formed along the sides of a glacier when it scrapes against valley walls

medial moraine

long narrow ridges formed in the middle of a glacier when two glaciers meet

terminal moraine

mark the maximum advance of a glacier and are formed at the glacier’s terminus

ground moraine

broad flat blanket of debris deposited beneath a glacier

end moraine

material left behind by glacier’s advance

what’s so special about a terminal moraine

key indicator of glacial activity

outwash plain

broad, gently sloping landform formed by sediments deposited by meltwater flowing from terminus of a glacier

what do we find on outwash plains

extensive areas of glaciofluvial sediments

glacial till

unsorted sediment deposited directly by a glacier

Where are tarns, paternoster, and kettle lakes found?

primarily in regions that experienced extensive glaciation during the last ice age

How do kettle lakes form?

depositional process; large, isolated block of ice breaks off a glacier and becomes partially buried by glacial sediment, when the overlying sediment collapses it forms a depression that fills with water

which erosional feature, formed by glaciers, can indicate which way the glacier was moving?

glacial striations

what evidence do we have of past glaciers?

glacial till; plucking and abrasion; moraines, drumlins, eskers, and outwash plains

which erosional and depositional features happen only in alpine glaciers

ciruqes, horns, aretes, troughs, hanging valleys, moraines, till, valley train deposits

What are the differences in beach material between depositional and erosional coastal zones?

erosional coasts are typically characterized by coarse material, depositional coats have fine material

what causes tides

gravitational pull of the moon and sun

neap tide

tide of minimal range that occurs when the sun and moon are at right angles to each other, producing lower high tides and higher low tides

spring tide

tide with the greatest difference between high and low water occurring when earth sun and moon are aligned during new and full moons

moon phase during neap tide

first and third quarter

3 controls on wave height

wind strength, wind duration, and fetch

wind fetch

unobstructed distance over which wind blows across a body of water

beach nourishment

adding sand to eroded beaches

sand dune restoration

rebuilding dunes and planting vegetation to stabilize them

hard stabilization

employs man made structures

soft stabilization

natural based techniques