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
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.
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.
