On a walk along the trails at Haw Ridge youll see lots of limestone outcroppings that contain fossils of ancient sea animals. Look closely at this photo, youll see some nice brachiopod fossils. Limestone is an indicator that an area was once under an ocean. Limestone was formed from seashells that settled to the ocean floor. Over long periods of time and pressure the calcium carbonate (CaCO3) in the seashells was transformed into limestone. Geologists test limestone by putting drops of hydrochloric acid on it; if it bubbles, the rock is limestone. The hydrochloric acid reacts with the calcium carbonate and releases carbon dioxide gas (CO2).

During the drought of 2007 we went to Piney Falls to see them with no water. I found these Horsetail Fossils in the rocks at the base of the falls. Normally there is too much water and spray to be able to take pictures there. These ancient plants were the distant relatives of today's Horsetails (Equisetum), also known as scouring rushes. They grew in this area long before the dinosaurs lived.