Glaciers and Shorelines Lab

Many changes have occurred over time in the area of Sandy Point. Which of the following statements about these changes is not true?

By late 2005, a breach occurred to the northeastern portion of the spit.

Which placemarked feature in the Jetty folder is the best example of a jetty?

C

What is the anthropogenic feature marked by the Managing Coastal Sediment placemark?

Groin

Which of the following statements best describes the development of the landform indicated by placemarks A and B?

It formed as the result of the deposition and distribution of sediments along the shoreline.

Which set of coordinates locates the source of the material that formed the moraine seen at placemark A?

60°38'6"N, 143°55'49"W

Sea levels have been slowly rising in recent years, and many lines of evidence suggest that sea level will continue to rise into the future. What effects will rising sea level have on Sandy Point and the land directly behind it?

As sea level along very flat coastlines rises, sand on the seaward edge of beaches can be washed inland during storms. As a result, bars such as Sandy Point will migrate inland, and the mainland immediately behind the bar will first be flooded, and then buried.

What will eventually happen to the crevasses, assuming that the ice beneath them continues to flow?

As the ice beneath the crevasses flows down gradient, the existing crevasses will close and new crevasses will develop near the placemarks.

Which of the following statements is most strongly supported by the historical imagery associated with the Japan Tsunami placemark?

At this location, evidence of tsunami flooding is evident more than three kilometers inland.

What feature is located at placemark E?

Avalanche debris consisting of snow and rock material

How does the presence of Bailey Hill appear to affect the land use pattern in this area?

Bailey Hill is undeveloped. The surrounding area is highly developed. This is likely due to the difficulty of developing an area with a steep slope.

Which of the following statements is most strongly supported based on an assessment of the data in the Human Impacts folder?

Coastal areas in the northern hemisphere have relatively higher levels of human impacts than coastal areas in the southern hemisphere.

What term properly describes the deep fractures in the glacial ice at this location?

Crevasses

Fly around the Mud Pond overlay area, zooming in and out as you explore. What term properly describes the landforms shown on the topographic map here?

drumlins

Many drumlins are asymmetrical, with a blunt end and a tapered end; the tapered end is usually oriented in the same direction that the glacier advanced. Survey the area with Google Earth and gauge the drumlin field. Which direction does it appear the glacier was moving?

southward

What is the name of the landform located at placemark J?

terminal moraine

What is the name of the landform located at placemark K?

terminal moraine

Which of the following diagrams correctly labels the direction of the longshore current and the motion of individual sand grains along the shoreline here?

the current is moving to the left.

How are the valleys in this area shaped?

Almost all of the valleys are U-shaped.

Which letter marks the location of the most recently deposited sediment in this area?

E

Which answer best explains why there appears to be so much more moraine debris accumulated at this location than further up on the glacier?

Ice melting far exceeds ice accumulation near placemark F. As glacial ice is transported from further up on the glacier to placemark F, it melts, and the earth material contained within it is deposited.

What is the elevation at this point (the highest point along the Transect A path)? Answer in feet.

312 feet

Calculate the area covered by the Mud Pond overlay (the rectangle of topographic map). Use the ruler tool to help you. Answer in square miles.

5.5 square miles

Which answer most accurately describes the relationship between the Long Island moraines, Cape Cod (the large peninsula shaped like a flexed arm), and Martha's Vineyard (the large island south of Cape Cod)? Use the map below as a guide.

Cape Cod and Martha's Vineyard also contain moraines. The moraines of Cape Cod and Martha's Vineyard were formed during the same glacial episode as the Long Island moraines. The northern moraine of Long Island was once continuous with the small peninsula protruding from the southwestern portion of Cape Cod. The southern moraine of Long Island was once continuous with Martha's Vineyard.

What term best describes the landform marked by placemarks A and B?

Hook or spit

Which answer most accurately describes the appearance and function of the landform at placemark J? It may be helpful to turn the Turquoise Lake Map overlay off and on as you explore the area.

It is an arc-shaped mound of material that blocks the outlet of the valley to the west. It appears to be a natural dam at the foot of the glacial valley that contains Turquoise Lake.

What are the origin and composition of the material that composes the landform at placemark J?

It is composed of an unsorted mix of rock material weathered, eroded, and deposited by the melting glaciers that flowed out of the cirques at placemarks I.

What is the origin and composition of the material that composes the landform at placemark K?

It is composed of well-sorted, fine particles of rock material that were weathered, eroded, and deposited by glacial meltwater from glaciers above the plain.

Notice that the widths of the tributary glaciers to the east and west of placemark B decrease as they join the main glacier in the foreground of this view. What is the most likely explanation for the observed changes in the width of the tributary glaciers' widths?

It is equally likely that the depth of the valleys the tributary glaciers are within increases as they approach the main glacier and that the tributary glaciers are flowing at an increasing rate as they approach the main glacier.

Which observation does NOT support the hypothesis that glaciation was more extensive in this area in the past?

Many mountain peaks east of the largest glaciers are capped in ice, even though the nearby valleys contain little to no ice.

What is the term that describes the long dark train of debris under placemark A?

Medial moraine

Which statement best describes the movement of sediment along the shore between placemarks A and B?

Sediment is transported from placemark B to placemark A.

Which path(s), if any, are drawn across a section of the valley that was formed largely by glacial ice? Which path(s), if any, are drawn across a section of the valley that was formed largely by running water?

The Profile A path is drawn across a valley that was formed largely by glacial ice. The Profile B path is drawn across a valley that was formed largely by running water.

Which answer most accurately describes the elevations of the moraine(s)?

The elevations are highest on western Long Island and get successively lower to the east. There seems to be only one high point along the Transect A path. To the east, one moraine forms the north shore of Long Island, and another branches off in an east-to-southeast direction near the Transect B path, crossing Long Island and finally forming the "south fork" of eastern Long Island.

Which observation does NOT suggest that these glaciers are acting more in a ductile nature than in a brittle nature?

The glaciers are located near the Pacific coastline.

How does Bailey Hill compare in length, width, and height with the landforms around Mud Pond?

The length, width, and height of Bailey Hill are all less than those of the landforms near Mud Pond.

How does the slope at each placemark compare with the slopes immediately above and below the placemarks? Why are the crevasses located at these locations?

The slope is steeper at the placemarks than it is between the placemarks. Crevasses tend to form near the placemarks because as glacial ice moves down steeper gradients, it speeds up. The brittle ice riding atop the flowing ice is thereby subjected to tensional forces (pulled apart) and responds by cracking open.

What is the most likely source of the sediment that makes up the landform marked A and B?

The source is the river that enters the ocean 2.5 kilometers northeast of Sandy Point.

How does the shape of the valley along the Profile B path compare to that of the Profile A path?

The valley along the Profile A path is U-shaped. The valley along the Profile B path is V-shaped.

Which of the following statements does not plausibly explain the observed changes to Sandy Point?

Wave size increased and larger volumes of sediment were delivered from farther offshore.

Placemarks A through F indicate the locations of six different glacial formations. Which answer correctly identifies each of the formations?

placemark A: horn peak placemark B: arête placemark C: col placemark D: tarn placemark E: cirque placemark F: hanging valley