Ice, Ice, Baby! Glaciers and Glacial Features Photo Source:

The Anatomy of a Glacier Glaciers advance (grow) when winter snowfall exceeds summer snow melt Glaciers advance (grow) when winter snowfall exceeds summer snow melt Glaciers retreat when summer snow melt exceeds winter snow fall Glaciers retreat when summer snow melt exceeds winter snow fall

Anatomy of a Glacier Glaciers are “rivers of ice” Glaciers are “rivers of ice” As snow accumulates, it compresses into ice As snow accumulates, it compresses into ice If the weight of ice gets great enough, it will flow downhill as a viscous fluid If the weight of ice gets great enough, it will flow downhill as a viscous fluid Flow is VERY slow Flow is VERY slow

The Anatomy of a Glacier Glaciers are divided into two zones – the zone of accumulation and the zone of wastage Glaciers are divided into two zones – the zone of accumulation and the zone of wastage Zone of Accumulation is where new snow is added Zone of Accumulation is where new snow is added Zone of Wastage is where ice melts Zone of Wastage is where ice melts Boundary between two zones is called the “equilibrium line” Boundary between two zones is called the “equilibrium line”

The Anatomy of a Glacier The end point of a glacier is called the “terminus” or the “toe” The end point of a glacier is called the “terminus” or the “toe” If the glacier ends at the ocean (or a lake) it can “calve” into icebergs (large and small) If the glacier ends at the ocean (or a lake) it can “calve” into icebergs (large and small)

The Anatomy of a Glacier Other parts of a glacier include: Other parts of a glacier include: Moraines Moraines Outwash plain Outwash plain Glacial Erratics Glacial Erratics

Moraines Moraines are piles of plucked material that form at the toe or sides of the glacier Moraines are piles of plucked material that form at the toe or sides of the glacier Basically “dumping grounds” for all the material that the glacier transports Basically “dumping grounds” for all the material that the glacier transports Contains unconsolidated material Contains unconsolidated material Moraines at toe are called “terminal” moraines Moraines at toe are called “terminal” moraines Moraines along sides are called “lateral” moraines Moraines along sides are called “lateral” moraines Terminal moraines can be very large hills Terminal moraines can be very large hills

Moraines

Outwash Plain Broad flat plain where glacial melt water flows and deposits fine debris from the glacier Broad flat plain where glacial melt water flows and deposits fine debris from the glacier

Glacial Erratics Glacial Erratics are rocks that are picked up by a glacier and deposited in a distant area Glacial Erratics are rocks that are picked up by a glacier and deposited in a distant area Rocks are distinct from the rest of the rocks in the area Rocks are distinct from the rest of the rocks in the area

Types of Glaciers Valley Valley Confined to a mountain valley Confined to a mountain valley Can only flow from higher to lower elevations Can only flow from higher to lower elevations Long and narrow, but can be thick Long and narrow, but can be thick Found in many mountainous regions Found in many mountainous regions

Valley Glaciers Personal Photograph

Types of Glaciers Continental (ice sheets) Continental (ice sheets) Unconfined by topography Unconfined by topography Flow outward in all directions Flow outward in all directions Very thick! Very thick! Found today only in Greenland and Antarctica Found today only in Greenland and Antarctica

Continental Glaciers

Glaciers and Erosion Glaciers are the greatest erosional force on the planet! Glaciers are the greatest erosional force on the planet! Glaciers can erode an entire mountain to dust (over the course of centuries, of course). Glaciers can erode an entire mountain to dust (over the course of centuries, of course). Glaciers can lift boulders many tons in weight. Glaciers can lift boulders many tons in weight.

How Does a Glacier Erode a Mountain?  Plucking  As the glacier moves over a surface, it “picks up” (sometimes large) pieces of rock  Remember frost wedging…  Pieces become stuck in the glacier and as it moves it…

How Does a Glacier Erode a Mountain?  Abrasion  … scrapes along the surface  Produces grooves in the rock face  Can also lead to “glacial polish”  Smooth surface that glistens like a mirror  Also can produce rock flour  Severely pulverized rock

How Does a Glacier Erode a Mountain? Glacial Grooves, Acadia National Park, Maine Photo by Hal Borns Rock Flour in Peyto Lake, Jasper National Park, Alberta, Canada Personal Photograph

How Does a Glacier Erode a Mountain?  Combination of Plucking and Abrasion on a mountain produces a feature called a Roche Moutonnee (Rock Sheep)  Mountain with a smooth gentle slope on one side and a rough, nearly vertical slope on the other

How Does a Glacier Erode a Mountain?  Diagram Source:  Photo Source:  Arrow indicates the direction of glacial movement

Erosion and Valley Glaciers Valley Glaciers will also pluck and abrade, but this results in different features Valley Glaciers will also pluck and abrade, but this results in different features Common features are aretes, horns, cirques and hanging valleys Common features are aretes, horns, cirques and hanging valleys Diagram Source: ier ier ier

Terms to Know Arete – narrow ridge produced by glacial action Arete – narrow ridge produced by glacial action Horn – arete that has been eroded on multiple sides to form a pyramid-like peak Horn – arete that has been eroded on multiple sides to form a pyramid-like peak Cirque – bowl like depression in the side of a mountain caused by a glacier grinding down Cirque – bowl like depression in the side of a mountain caused by a glacier grinding down Hanging Valley – a valley carved into a mountain that stops abruptly above the current valley level Hanging Valley – a valley carved into a mountain that stops abruptly above the current valley level

Can you identify the picture? Cirque Horn Hanging Valley

Erosion and Valley Glaciers One of the most tell- tale signs of past glaciation is a wide U-shaped valley. One of the most tell- tale signs of past glaciation is a wide U-shaped valley. Rivers carve narrow V- shaped valleys Rivers carve narrow V- shaped valleys With a glacial valley, the river (if present) is very narrow compared to the valley With a glacial valley, the river (if present) is very narrow compared to the valley

Depositional Features of Glaciers Glaciers not only erode, but they deposit as well. Glaciers not only erode, but they deposit as well. Deposition occurs at the toe of the glacier and along sides of glacier Deposition occurs at the toe of the glacier and along sides of glacier

Deposition and Glaciers  Diagram Source:

More Terms to Know! Esker – winding narrow mounds of debris left by a tunnel in a glacier Esker – winding narrow mounds of debris left by a tunnel in a glacier Drumlin – whale shaped hill of deposited sediment; can be very high Drumlin – whale shaped hill of deposited sediment; can be very high

More Terms to Know! Kame – hills formed by debris in the hole of a glacier left behind when the glacier recedes Kame – hills formed by debris in the hole of a glacier left behind when the glacier recedes Kettle – depression in the ground caused by the melting of buried ice; can be filled with water Kettle – depression in the ground caused by the melting of buried ice; can be filled with water

What Am I? Kame Kame

What Am I? Esker Esker

What Am I? Kettle Kettle

What Am I? Drumlin Drumlin Arrow shows the direction of glacial retreat Arrow shows the direction of glacial retreat Can you name 3 ways a drumlin is different from a roche moutonnee? Can you name 3 ways a drumlin is different from a roche moutonnee?

Wrapping Up… What are two types of glaciers? What are two types of glaciers? Name 2 ways a glacier erodes. Name 2 ways a glacier erodes. Name 2 erosional features. Name 2 erosional features. Name 2 depositional features. Name 2 depositional features.