Glacier Lesson Worksheet -- Answer key and hints

Below are suggested examples of answers to the questions on the worksheet.
Students should be referred to the USGS Glacial Glossary (http://www.teachingboxes.org/catalog.jsp?id=DLESE-000-000-008-844) to search keywords
Teachers might point students to keywords as hints to help guide students to answers.

Be sure students examine both the examine Types of Glaciers web page and use the Alphabetical Index.

view is looking up, over the toe of Carbon Glacier toward the peak of Mount Rainier in Washington Question 1

This view is looking up, over the toe of Carbon Glacier toward the peak of Mount Rainier in Washington. Why do you think there are rocks on top of the glacier? How did they get there?

Keywords: Till and Moraine

Answer: As the glacial ice moves, it scrapes and grinds the bedrock, and these loosened material become mixed into the ice. At the toe of the glacier, the ice melts, leaving the rock behind. This is called a moraine or till.

 

picture of the beach near Montauk Point on Long Island Question 2

This is a picture of the beach near Montauk Point on Long Island (at the eastern end of Long Island, New York). Usually rocks on a beach are well rounded by wave action. These are not. Where could they have come from?

Keywords: Till, Terminus, and Moraine

Answer: The deposits on Long Island are the deposits of a glacier moraine. The rocks were carried there by glacial ice and deposited at the terminus of a continental glacier.

Valley in North Cascades National Park in Washington Question 3

This valley is in North Cascades National Park in Washington. What shape is this valley, and what gave it the shape?

Keywords: U-Shape Valley, Hanging Glaciers, and Valley Glaciers

Answer: The valley is a U-shaped valley. It was carved by a glacier in the past, the the glacier has since melted.

This rock and wall is at the Cloisters Museum in New York City Question 4

This rock and wall is at the Cloisters Museum in New York City (on Manhattan Island). What are the "scratches" called, and how do they form? Why are they in New York City?

Keywords: Glacial Grooves, and Striations

Answer: Glaciers once covered the New York City area. The moving ice scraped the bedrock producing glacial groove and striations. The glaciers that once covered New York have since melted.

This picture shows two types of rocks on a mountaintop in northern New Jersey.

Question 5

This picture shows two types of rocks on a mountaintop in northern New Jersey. This is a large boulder of a layered sandstone (a sedimentary rock) resting on granite bedrock (an igneous rock). Sandstone, like this boulder, is found on a mountain about 30 miles away. How this boulder might get here?

keywords: Erratic

Answer: A continental glacier once covered the northern New Jersey region. As the glacier moved south, the sandstone boulder was plucked from its bedrock source, and transported by the moving glacial ice to its current location. The glacier melted, leaving the boulder on the mountaintop.


This view is looking north along the Husdon River in Southern New York Extra Brain Teaser

This view is looking north along the Hudson River in Southern New York. Although the "Hudson" is a "River" - early explorers of the region thought that the broad river might be a passage for boat travel across North America. Although they were disappointed, they did note that the Hudson River is salty all the way to its headwater regions near Albany, New York (nearly 200 miles from the ocean). Could you explain why the Hudson River is salty?


Keywords: Fjord

Answer: The Hudson River is a Fjord. The valley was partially carved by a southward advancing ice sheet (or continental glacier). When the glaciers melted, rising sea level flooded the Hudson River Valley with sea water.