I was realy suprised when I went to Dellwood and found the rock I found... But like you Mnster said, it was part of an impoundment/lake. Years ago they built a lagoon for recreation and in the process cleared all teh dirt from the rocks.. Given the vast majority is sheer cliffs but, several car sized sections have sheered off and tons and tons of smaller basketball sized material has piled up. Im going to try to get some time this Sunday to go back and clear some of the rock and take some better pictures.