Rock Sample at SHP
Julia Brazo is a M.S. student at UNH and a member of Joe Licciardi’s (CC'ed) research group in the Earth Sciences Department. Julia will be collecting rock samples on boulders that are found in Stratham Hill Park. Ms. Brazo will be collecting rock samples for her master’s thesis which seeks to understand the glacial history and local sea-level changes of the Seacoast region of NH.
During the Last Glacial Maximum (roughly 20,000 years ago), the Laurentide Ice Sheet engulfed northern North American including New Hampshire. The main objective of the project is to reconstruct the timing and pattern of glacial retreat and marine regression associated with deglaciation in the Seacoast of New Hampshire following the Last Glacial Maximum (roughly 20,000 years ago). An understanding of past glacial systems has implications to those that exist today in Alaska, the Arctic, and Greenland.They will be using a method called surface exposure dating to determine when glacial erratics/boulders were exposed to the elements after they were deposited by the glacier (i.e. no longer covered by water or ice). Following the Last Glacial Maximum, the sea level was much higher, so the seacoast was covered with water. This sea-level maximum of 70 meters above present-day is what we call the marine limit. Stratham Hill is a drumlin, an elongated hill made up of glacially deposited sediment, and a great place to find glacial erratics. Stratham Hill has a maximum elevation of 88 meters. Samples from Stratham Hill Park are both above and below the marine limit which will help both determine the timing of ice retreat and the rate of marine regression.
As for how samples are taken, the scientists will use a simple rock hammer and chisel to chip off rock pieces from the surface (which are usually less than a few cm in depth). If the rock is really tough, we use a small battery-powered rock saw to create cuts that act as an edge for the chisel method. We aim for samples less than 1 kg. And after the sample is taken, we use the rock hammer to make the rock appear as if it hasn’t been cut or a piece removed (making it look natural, like erosion, and as undisturbed as possible). They will be targeting sample locations that are off trail as to not disturb other visitors and aim to have a low impact on the overall area.
Ms. Brazo sampling will be taking place on November 20th and 21st. The Stratham Select Board review and approved Ms. Brazo's request at their regularly scheduled meeting on November 15th.