Student Links

OVERVIEW:

The initial plans for the cruise had been to map the sea floor to the east of Franklin and Beaufort Islands located at the northern end of McMurdo Sound, in the Ross Sea.  Franklin and Beaufort are both volcanic islands, and would serve as geographic reference points for the cruise. In 2003, sea ice conditions were some of the heaviest in years, limiting the ship's ability to navigate to areas that were potentially interesting for the scientists.  The cruise was postponed until, 2004.  Reduced sea ice early in the 2004 Antarctic field season improved the chances that the research would be successful.

Early in October of 2003, iceberg B15 began to move from along the Ross Ice Shelf where it had calved off in 2001.  B15 was over 100 miles long and 30 miles wide.  Had it stayed near the ice shelf it would have had little effect on the cruise.  By January 2004, B15 had broken into two large pieces that moved toward Franklin and Beaufort Islands.  Floating in 200 to 300 meters of water, the bergs became grounded within miles of the islands. 

The scientists approached the cruise with optimism, and focused on working in open water in as large an area of the Ross Sea as the sea ice and bergs would permit.

The calving of B15 is an example of one way that glaciers change over time.  Calving or breaking of chunks of ice from the edge of the glacier is a normal process that results from melting and stresses in the ice.  These are spectacular events that occur in short periods of time, but the majority of the processes that shape glaciers and the land around them and under them are measured in centuries not days.

10000 years ago the southern most edge of the last continental glacier to cover North America extended southward through Wisconsin.  The glaciers in Antarctica are hundreds of thousands of years old, but the processes that we observe in Antarctica today are the same as those that shaped the North American continent during the last ice age.

As the glaciers retreat, they deposited materials scoured off the land surface and transported by the moving ice to the glacier edge.  The edge of the receding glacier became the resting place for rocks of all sizes.  Depending on the rate at which the ice melted at the edge, different glacial features were left and are observable as surface features in many parts of the Midwest today.

Some of the common features include drumlins, eskers and moraines.  Drumlins were formed beneath the moving ice.  They are characterized by a teardrop shaped plan or map view. The narrow end of the teardrop has a very gradual slope pointing in the direction that the glacier receded and a very steep slope and more rounded end on the side where the glacier advanced.  Eskers and moraines form at the edge of the receding glacier and form on the surface due to the flow of water melting from the glacier.

Much of the area that was surveyed during the cruise had never been studied using the sonar and seismic technology available aboard the ship.  The cruise would produce new maps of the sea floor showing details that had never been seen.

Much of the attention on the cruise was paid to identifying volcanic features like marine sea mounts and vents and structural features of tectonic origin like faults.  What became clear during the cruise was that the sea floor in this area had been dramatically affected in some of the areas by past glaciers. 

 

The scientists aboard the ship were intrigued and excited about their findings, but they were outside of the scope of the planned research for the cruise.  What were observed on the new sea floor maps were structures that may be glacial in origin.  One of the features that were of particular interest was a cluster of circular structures that show similarities to drumlins.  Were they drumlins?  This was a topic of discussion while on the cruise, but this data would have to be left to other scientists.

National Standards

• Content Standard A - Understandings about Scientific Inquiry - Scientists rely on technology to enhance the gathering and manipulation of data.
• Content Standard C - Interaction of Energy and Matter - Waves, including sound and seismic waves, waves on water, and light waves have energy and can transfer energy when they interact with matter.
• Content Standard E - Understanding About Science and Technology