Report 48575: Fisherman on Lake Arthur startled by series of possible wood knocks and rock clacks

While fishing on Lake Arthur at Moraine State Park I heard wood knocks and rock clacks. It seemed that they were answering each other. I would hear 2 wood knocks then maybe 10 seconds later, to the west about 200-300 yards I would hear 3 rock clacks. This sequence continued for about 8-10 minutes. The sounds stopped when a boat went past mine. I do believe in Bigfoot, I always have. However this is the first time that anything like this has happened to me. It disturbed me so much that I started up my boat and moved to another part of the lake.