What is a CORK?

posted Oct 4, 2017, 7:06 AM by Beth Orcutt
by Anne Hartwell

Good day, Girl Scouts of Maine.  I am so excited to be a part of the communication team that gets to talk science with YOU!  Ocean science is a really cool field of study because there is a wide variety of topics on which you can focus. Anything from ocean motion (physical oceanography), ocean saltiness (chemical oceanography), rocks and minerals (geological oceanography), the millions of critters that live in it (biological oceanography). You can even be an engineer and still work on the ocean.  This post is going to look at how engineering plays an important role in ocean sciences- we’re going to talk about CORKs!

A CORK is a stopping device that caps the holes scientists drill into the sea floor - and their function is to stop the flow of cold bottom water in the drilled hole. When holes are drilled into the seafloor, the circulation of water that existed before the drilling is disturbed. This is a problem because scientists are interested in looking at the undisturbed flow. The CORK allows the original flow to be re-established. Once a hole is drilled and the CORK is emplaced, the scientists can do long-term monitoring of the movement of water through the subseafloor.

The official acronym for CORK is Circulation Obviation (because it prevents circulation) Retrofit Kit (because it can be installed onto a hole many years after the fact). CORKs are outfitted with a variety of instruments to monitor the inside of the hole. Instruments like pressure gauges, temperature cables, and data loggers and hang down deep into the hole. There is also a valve near the CORK top that lets the scientists to sample the water the is circulating in the hole. The image to the right from an article in Science News shows a cartoon of a CORK

On this cruise, researchers are returning to North Pond to sample water from the valve and to recover the instruments strung from several CORKs – the instruments have been in the hole for six years! Sampling and recovery done with the help of the ROV Jason-II - you’ll learn more specifics about Jason-II in a future post! To sample the water from the CORK, Jason-II attaches a sampling tube and turns a valve to initiate the flow. To recover the strings, Jason-II pulls the instrument string out of the hole and ascends to the sea surface - trailing the string behind. When the ROV reaches the surface, the strings are carefully brought on board by the experienced boat crew. Check out a future post to learn about how scientists plan to use the data and fluids collected at North Pond!

Below is a picture of the original CORK sketch made by our colleagues Keir Becker and Earl Davis - like many great ideas (like the Harry Potter Series), it started on a dinner napkin.