Potsdam sandstone, sedimentary rock, Cambrian, deposited 500 million years ago. The Potsdam, or Nepean sandstone is found at Inverary, near Kingston which is the origin of it's name as the Kingston Sandstone. It was laid down in the Cambrian Period. The sandstone shows typical sedimentary features such as ripple marks, low closely - spaced ridges created in sand by the action of waves or currents. Cross bedding layers of sand accumulated at an angle to the bedding. Sandstone pillar columnar structures are also found in the sandstone. These rocks were collected from the quarry of Rideauview Contracts. There are other occurrences of the rock and they are all east of Kingston. A special thanks goes to John Motz and Jerry Pilny for acquisition and transport of this rock.
