weathering erosion glaciers - weebly
TRANSCRIPT
What is weathering? Weathering – the breakdown of rock material through chemical and physical processes
-‐ Physical – when a rock is broken down into smaller pieces by temperature changes, pressure changes, plants, animals, wind, water and ice.
-‐ Chemical – when a rock is broken down into smaller pieces by chemical reactions with oxygen and acids
What kinds of landforms does weathering create?
-‐ Without weathering, we would not have soil (we would just have lots and lots of really big rocks).
-‐ Physical weathering – creates soil, smaller rocks, etc. -‐ Chemical weathering – creates caves and causes rocks with
iron to rust. What is erosion? Erosion – when sediment is moved from one place to another With water
-‐ Streams and rivers – o Creates canyons, valleys, floodplains
-‐ Groundwater – o Creates caves and sinkholes
-‐ Waves and Currents – o Creates beaches, sea-‐cliffs and sea caves
With wind o Creates sand dunes, desert pavement
With ice -‐ Glaciers move because of gravity (pushes them outward) -‐ As they move, they pick up materials. They keep moving and
these materials cause abrasion. -‐ Abrasion -‐ when one thing is rubbed against another,
causing it do get worn down -‐ -‐ Glacial drift – glaciers then deposit all of the things they had
picked up over time. -‐ Continental glaciers – thick sheets of ice spread over large
areas o Create smooth, flat landscapes o moraines – hills made of glacial till that is left over
after a glacier leaves o kettle lakes -‐ when a hunk of ice is left or buried and
creates a lake or pond
Title: Weathering, Erosion and Glaciers – Minnesotan Landscapes
Essential Vocabulary and Questions
Key Information, Models and Definitions
What causes a glacier to form?
-‐ If temperatures are cold enough for snow to fall and then stick around the following year, it will begin to build up over time.
-‐ Once enough snow is built up, the snow at the bottom will start to get compressed into ice.
-‐ As the glacier continues to grow, it begins to push out into open spaces (like Minnesota).
How have Minnesotan landscapes been changed by weathering, erosion and glaciers?
1) Canadian Shield (NE) a. Very old (545 million to 2.5 billion years old)
bedrock that was the first part of the “baby” North American Continent
b. Erosion from the last glacier has exposed a great amount of this ancient rock
2) Itasca Moraines (N- Central) a. When one of the last glaciers left Minnesota, it
deposited a great amount of sediment in and around Itasca State Park
b. The hills and lakes that you will find in this region are moraines and kettles
3) Glacial Lake Agassiz (NW) a. As the glacier melted overtime, water became
dammed up behind ice and debris left from the glacier
b. This created a lake that was one of the largest glacial lakes of our continent
c. When it drained, it left behind a low, flat area 4) Caves and Sinkholes of the “Driftless” area (SE)
a. Rain is slightly acidic, so when it comes in contact with calcium carbonate, it erodes it (chemically).
b. Often, this will cause areas underground to open up (creating caves)
c. When it can no longer support the ground above it, it collapses into a sinkhole.
Essential Vocabulary and Questions
Title: Weathering, Erosion and Glaciers – Minnesotan Landscapes