Christine Hedge, September 9-11, 2009

NOAA Teacher at Sea
Christine Hedge
Onboard USCGC Healy
August 7 – September 16, 2009 

Mission: U.S.-Canada 2009 Arctic Seafloor Continental Shelf Survey
Location: Chukchi Sea, north of the arctic circle
Date: September 9-11, 2009

Positions 
From Latitude: 790 6’N/ Longitude: 1550 47’W
To Latitude: 780 3’N/ Longitude: 1590 41’W

Alex Andronikov labels and bags rock samples for further study.
Alex Andronikov labels and bags rock samples for further study.

Science and Technology Log 

Exploring the Unknown 
Geologically speaking, parts of the Arctic Ocean are some of the least explored areas on earth because they are often covered with thick ice. Geologists know there is an ultra-slow spreading center (where seafloor pulls apart) called the Gakkel Ridge.  They know where major features such as abyssal plains, plateaus, and ridges are, but the story of how this area formed is still the subject of much discussion. Where exactly are the plate boundaries in the Arctic?  Which direction are they moving?  Which forces formed the Arctic Basin?  These are great questions that geologists continue to investigate. In 7th grade we study plate tectonics.  Our textbooks contain maps showing where the plates are pulling apart (divergent boundaries), pushing together (convergent boundaries), and sliding past one another (transform boundaries). I had never noticed before this trip that clear plate boundaries are not shown under the Arctic Ocean.

FOR MY STUDENTS: There are some great animations showing plate movements at this site.

Looking Back in Time with Rock Samples 

Kelley Brumley and Alex Andronikov are geologists on board the Healy. They have been analyzing the data collected by the echosounding instruments to better understand the forces at work here. But what they have really been looking forward to is seeing what type of rock the seamounts, ridges, and plateaus below the Arctic Ocean are made of, and how these features were created.

Our first 2 dredge sites brought up muddy sediment and lots of:

  • Ice rafted debris: These are rocks that are frozen into ice that breaks from shore and carried out to sea. They can come from glaciers, or river deltas or any shoreline.  Some show glacial striations (scratches left behind by glaciers).
  • Coated sediments: These are crumbly, compressed mounds of sediment coated with a dark precipitate.
Dredge #2 was a muddy affair.  Using the hose, I helped separate the sediment from the rocks.  That’s me in the turquoise gloves!
Dredge #2 was a muddy affair. Using the hose, I helped separate the sediment from the rocks. That’s me in the turquoise gloves!

The next 3 dredges broke off rock samples from the steep slopes over which they were dragged. This was what the geologists were hoping for – samples of bedrock.  The rock samples that were dredged up show us that the geological history of the region is very complex.  Analyzing the chemistry and mineral composition of these rocks will help to answer some of the questions Kelley, Alex, and other Arctic geologists have about this part of the Arctic Ocean.  The rocks are cleaned, carefully labeled, and shipped to Stanford University, the University of Michigan, and the USGS (United States Geological Survey) for further study. Who knows, maybe the rocks that were collected today will help to clarify models for the geologic history of this part of the Arctic Ocean.

Personal Log 

On September 11, I was able to call my students in Indiana. Jon Pazol, (ARMADA teacher at sea) has an Iridium satellite phone that he graciously allowed me to borrow.  How fun to stand on the helicopter pad of the Healy and field questions from Carmel, Indiana.

Rock samples from a successful dredge operation
Rock samples from a successful dredge operation
Dredges sometimes bring up more than rocks and sediment. This arthropod came up with one of the dredge samples.
Dredges sometimes bring up more than rocks and sediment. This arthropod came up with one of the dredge samples.
Calling my students.  You can see in the background that there is much more ice than a few days ago.
Calling my students. You can see in the background that there is much more ice than a few days ago.

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