The Arthur Ross Terrace will be closed this morning, Tuesday, October 21, for a private cultural observance. You many observe smoke and/or fire coming from the Terrace at that time. The FDNY has been notified in advance, and all safety precautions are in place. The Terrace will reopen at 1 pm.
The surface scratches on this sample, from an outcrop of granite gneiss, are called glacial striations. During the last Ice Age, rocks and pebbles embedded in the underside of a glacier were dragged across the outcrop, forming these grooves.
Topic: Earth Science
Subtopic: Earth Formation/Evolution
Keywords: Geological cross sections, Geology, Glacial epoch, Gneiss