Close modal Add to library You don't have any lists yet. Create one in My Library. Go to My Library Set reading status Close modal Add to library You don't have any lists yet. Create one in My Library. Go to My Library Set reading status Details Summary Read Discussions Reviews Geological Survey Circular Language English Published in 1951 Pages 578 Subjects Geology Add Discussion No discussions yet for this book. Close modal Delete Discussion Are you sure you want to delete this discussion? This action cannot be undone. Cancel Delete Add review No reviews yet. Be the first to review this book! Close modal Delete Review Are you sure you want to delete this review? This action cannot be undone. Cancel Delete