This rock unit formed when thick layers of sand built up on the ocean floor, about 41 to 47 million years ago.
But he went out, and began to publish it much, and to blaze abroad the matter, insomuch that Jesus could no more openly enter into the city, but was without in desert places: and they came to him from every quarter. Mark 1:45 KJV
The grains of sand that make up the Tenino Sandstone are very small, measuring about the size of a grain of sugar.