Wetlands, Peat, and Tundra Part 2 Flashcards
What are the major landscape building features in northern systems?
glaciation and de-glaciation (above ground)
permafrost and melting permafrost (below ground)
__% of earth’s surface used to be covered by ice sheets, today only __% is covered
30
11
Pleistocene glaciation was ___-___ yrs ago, and was the southern extent of the ice sheet in north america
What were the 2 ice sheets associated with it?
1million to 18,000 yrs ago
Laurentide Ice sheet- eastern North america
Cordilleran ice sheet- western north america
*between them= rockies
The _____ glaciation covered most of the northern half of north america 85,000-___yrs ago
Wisconsin glaciation
7000
= northern systems are still relatively young
Ice is heavy, so ___ the crust of the earth. When the ice melts, the earth __ resulting in lots of changes
compresses
lifts
T/F
The cypress hills were not glaciated by the laurentide ice sheet
true
not glaciated at all= lots of species could survive
What are some of the consequences of the distribution of the proglacial drainage and the proglacial lakes?
- glacier melts= more water –> impacts fish etc
- permitted fish etc to migrate northwards across present-day drainage divides
- dispersal of some tree species into the deglaciated areas
Glaciation stripped away ___, deposited glacial ___, and created many ___ basins and ____
soil
till/ drift
lake
riverbeds
Glaciers began to recede ~___years ago and forest cover gradually regenerated over Canada
20,000
The boreal forest took on its present character ~___yrs ago making it a ___ ecosystem
5000
young
What are 4 signs of glaciation left on the landscape (evidence)?
- glacial fluting
- glacial moraines
- raised beaches- isostatic rebound
- eskers (water moves under the glacier, carrying sill)
Periglacial= ___of a glacier
edge
Permafrost=
earth material (soil, bedrock, clay, etc) that’s been below 0C for >2yrs, so it has become ice-cemented
Permsfrost can be ___-___ deep, with a much shallower ___ ___ that melts seasonally
200m-1km
active layer
T/F
1. frozen land below glaciers is permafrost
2. Many trees are adapted to live in permafrost
- true
- false
- not many can live here; nowhere for the roots to go