Thousands of years ago, this area was covered by a chalk ocean, which accounts for the chalk bluffs and beds. The chalk bluffs are still a fossil hunter's delight. This lofty calcerous limestone bluff has the appearance of an old English castle. A must see. Voted one of the 8 Wonders of Kansas. Location: Castle Rock: Take I-70 Quinter exit 107 (Castle Rock Road), go 15 miles south to the intersection of GO 80 and GO K, then 4 miles east to Castle Rock sign, and north across a cattle guard (dry weather road only).