Slideshow: Getting to the Core of It

Today, Luke McKay, Bill Inskeep, and Pat Shanks collected gravity cores in and around the focus site northeast of Stevenson Island. Gravity coring is a method that extracts a cylindrical mass of sediment up to two meters (6.5 feet) long by dropping a hollow, 100+ pound tube into the sediment from 5-10 meters (16-33 feet) off the lake floor. The downward momentum of the tube drives it into the sediment, filling the inner chamber with material that can be later used for experiments.

Before collecting any samples, the team first built a wooden covering to protect the back of the boat from the heavy coring equipment. Once the covering was installed, it was time to push off and head to the study site. The depths in this area range from 80 – 120 meters (262-394 feet), depending on what part of the venting field you are in. When we arrived at the first site we lowered the rig to 5 meters (16 feet) above the lake floor, let it free fall into the sediment, and raised it to the surface. The whole process took about 20 minutes. Everyone on the boat was hopeful as the inner tubing was removed from the gravity core to reveal that the first core had brought up … NOTHING.

Another two attempts were made, altering the height from which the rig was dropped and even trying to slowly lower it into the sediment, which all came up empty. Luke, Bill, and Pat concluded that the sediments in the location were too hard to properly core. After much deliberation, it was decided that we would move on to the next site. Once there we lowered the rig and dropped it at the new location, the coring attempt was a success! We recovered a core measuring about 40 centimeters (16 inches). While the learning curve was steep for the day, the team recovered five cores, providing valuable data about the biology and chemistry of the venting field.

Story and photos by Louis Garcia, Louisiana State University. Work was completed under an authorized Yellowstone Research Permit.

Luke Mckay(front) and Bill Inskeep(back) take measurements to build the wooden covering to protect the back step of the boat. Work was completed under an authorized Yellowstone Research Permit.

The top of the gravity coring rig with the black valve at the top visible. This valve releases pressure as the core descends into the sediment to ensure as much sediment as possible is captured. Work was completed under an authorized Yellowstone Research Permit.

The cutting edge of the gravity core (left). This round blade is used to more efficiently pierce the sediment and is quite sharp. Work was completed under an authorized Yellowstone Research Permit.

Pat shanks recovering every ounce of sediment from the core catcher for later experiments. Work was completed under an authorized Yellowstone Research Permit.

Luke McKay (right) and Bill Inskeep (left) inspect and clean the captured gravity core taken from a hydrothermally active area of the lake. Work was completed under an authorized Yellowstone Research Permit.

Bill Inskeep (left) and Luke McKay (right) measure the captured sediment core to record in their log book. Work was completed under an authorized Yellowstone Research Permit.

Recovering the last bit of sediment from the core catcher. The hard sediment encountered, as can be seen on the catcher, prevented the core from fully penetrating the sediment. Only sediment from the catcher was recovered for this drop. Work was completed under an authorized Yellowstone Research Permit.

Hard, hydrothermally altered sediments from an active venting area make for awesome samples, but difficult coring work. Work was completed under an authorized Yellowstone Research Permit.