What do you want to do when you've finished? http://www.flaviamajlis.com/english-essays-for-students-pakistan/ write essay for college entrance  According to Benson, a white layer of carbonate made of limestone precipitated from the ancient, overflowing Winnemucca Lake had coated some of the petroglyph carvings near the base of the boulders. Previous work by Benson showed the carbonate coating elsewhere in the basin at that elevation had a radiocarbon date of roughly 11,000 years ago.