Tuesday March 8, 2011 (Types of Glaciers; Formation of Glaciers)

The Launch Pad Tuesday, 3/8/11 Define the term “Karst topography.” List three possible sources of groundwater contamination. Name a situation where water is being treated as a non- renewable resource. Karst topography refers to landscapes that to a large extent have been shaped by the dissolving power of groundwater. seepage from landfills depletion of aquifers due to taking more water from the ground than is being replenished. seepage from fields that have been fertilized and/or sprayed with pesticides seepage from septic tanks.

Announcements We will have a test this Friday.

Assignments For This Six-WeeksDate IssuedDate Due Video Quiz - Lakes, Rivers, and Other Water Sources 2/27 WS - Running Water and Groundwater (Part 1) 2/253/4 PowerPoint Project – Rivers (P5 only) 2/283/3 WS - Running Water and Groundwater (Part 2) 3/23/9 Video Quiz - Groundwater3/3

Cornell Notes Ice

Sea kayakers look at the face of McBride Glacier along Muir Inlet in Glacier Bay National Park, Alaska.

Glaciers Glaciers are part of both the hydrologic cycle and the rock cycle. A glacier is defined as a thick mass of ice that forms over land from the compaction and recrystallization of snow, and shows evidence of past or present flow.

Types of Glaciers Valley, or alpine glaciers form in mountainous areas

Types of Glaciers Ice sheets, or continental glaciers, are very large. They are masses of ice covering more than km². For example, ice sheets cover Greenland and Antarctica.

The only present-day continental ice sheets are those covering Greenland and Antarctica. Their combined areas represent almost 10% of Earth’s land area. Figure 6.2

Types of Glaciers An ice cap is an ice mass that covers less than km² of land area (usually covering a highland area.)

Types of Glaciers Piedmont glaciers are a type of glaciation characteristic of Alaska - large valley glaciers meet to form an almost stagnant sheet of ice.

Malaspina glacier in south-eastern Alaska is considered a classic example of a piedmont glacier. Piedmont glaciers occur where valley glaciers exit a mountain range onto broad lowlands, are no longer laterally confined, and spread to become wide lobes.

This map shows a portion of North America’s present-day coastline compared to the coastline that existed during the last ice age maximum years ago.

The North American coastline that would exist if present-day ice sheets in Greenland and Antarctica melted.

The Formation of Glacial Ice As air infiltrates snow, snowflakes become smaller, thicker, and more spherical. The air is forced out of the snow. The snow then recrystallizes into a much denser mass of small grains called firn. Once the thickness of the ice and snow exceeds 165 feet, firn fuses into a solid mass of interlocking ice crystals, which we call glacial ice.