Jessie Soder: Geology on Georges, August 17, 2011

NOAA Teacher at Sea
Jessie Soder
Aboard NOAA Ship Delaware II
August 8 – 19, 2011 

Mission: Atlantic Surfclam and Ocean Quahog Survey
Geographical Area of Cruise:  Northern Atlantic
Date: Wednesday, August 17, 2011

Weather Data
Time: 12:00
Location:  41°19.095 N, 71°03.261
Air Temp:  22°C (°F)
Water Temp:  21°C (°F)
Wind Direction: South
Wind Speed: 7 knots
Sea Wave height:  0
Sea Swell:  0

Science and Technology Log

Gulf of Maine: Including Georges Bank

So far, we have spent this entire trip on Georges Bank.  This famous geographical location off the east coast of the United States is something that I had only heard about before this trip.  After several tows over the past week I have been able to see a variety of materials brought up from the ocean floor of Georges Bank.  I have seen loads of clams, empty shells, sand, mud and clay, and smooth polished rocks.  We have even pulled up a few boulders that must have weighed a couple of hundred pounds.  It was the smooth polished rocks that caught my attention. How would a rock from the bottom of the ocean become smooth and rounded?  It probably meant that Georges Bank must not have always been the bottom of the ocean.

During the Wisconsin Glaciation the ice reached its maximum around 18,000 years ago.  The Laurentide ice sheet paused in the area of Georges Bank and Cape Cod and left behind a recessional moraine that created these landforms.  This ice also had several meltwater streams flowing from it and these streams were responsible for the polishing the rocks and cutting some of the canyons found on the seafloor today.  The Northeast Channel off the northeast side of Georges Bank was the principle water gap for most of the meltwater.

Smooth Polished Rocks From the Ocean Floor

Georges Bank is a huge oval-shaped shoal bigger than Massachusetts that starts about 62 miles offshore.  It is part of the continental shelf and its shallowest areas are approximately 13 feet deep and its deepest areas 200 feet.  In fact, thousands of years ago Georges Bank used to be above water and an extension of Cape Cod.  About 14,000 years ago the sea rose enough to isolate this area and it was home to many prehistoric animals such as mastodons and giant sloths.  Today, traces of these animals are sometimes found in fishing nets!  These animals died out about 11,500 years ago when the sea level rose further and submerged the area.

Georges Bank is a very productive fishing area in the North Atlantic.  (The Grand Banks is more productive, but not as geographically accessible as Georges Banks.)  Why is Georges Bank a prime feeding and breeding area for cod, haddock, herring, flounder, lobsters, and clams?  It has to do with ocean currents.  Cold, nutrient rich water from the Labrador Current sweeps over the bank and mixes with warmer water from the Gulf Stream on the eastern edges of Georges Bank.  The mingling of these two currents, plus sunlight, creates an ideal environment for phytoplankton, which is food for the zooplankton.  In fact, the phytoplankton grow three times faster here than on any other continental shelf.  All of this plankton feeds the ecosystem of fish, birds, marine mammals, and shellfish that flourish on Georges Banks.

Personal Log

Yesterday we left Georges Bank for stations off the coast of Rhode Island.  After dark, I stepped out on the back deck and Jimmy pointed out the lights of Nantucket and Martha’s Vineyard.  We were in sight of land for the first time in a week.  It wasn’t long before people had their cell phones out and were making calls.

A few times during this trip I have thought about sailors in the past and how they would leave for months, and even years, at a time and not have contact with their families and loved ones until they returned.  I have had email contact this entire time, yet I am really excited to go home to see those that I miss.  I can hardly imagine what it would be like to be gone for a year with no contact at all.

Throughout this trip I have been getting to know others on this cruise.  I have learned that several of them have families and young children at home.  Many of them are at sea for many weeks, or months, a year.  After being on this cruise, I have gained a lot of respect for people who choose to work on the ocean for a living.  It takes a certain type of person who can work hard, maintain a positive attitude, and live away from their home and loved ones for extended periods of time.  It has been an honor to work with these people.