BLOG 4: Dredging the Heemskirk

By Emily Fewster

This morning we are dredging the side of the Heemskirk Seamount (an underwater, extinct volcano), the top of which is some 2,600m below sea level….so that is a lot of cable we have paid out to get the dredge cage deep enough down its flank. Earlier, the RV Investigator undertook 4 hours of bathymetric mapping of the area to select and plan the best dredge site.

In the 3D mapping image above you can see our dredge path as a blue line across a 750m path up a small section of Heemskirk from point A to A^’. The light brown colour indicates the top of the seamount at 2,623m deep and the darker blue is the surrounding sea floor at around 4,800m deep.

The Heemskirk Sea Mount has been selected as a dredge site because the science team suspect it may be the youngest in the chain of sea mounts called the Lord Howe Rise, running down the East coast of Australia. This can be confirmed with radiometric dating of rock samples back on dry land.

Rocks are due up on the back deck anytime now so I had better get going. My job today is photographing the rock samples once they have been cut, cleaned, labelled and described.