 It should not be confused with the much smaller Rattlesnake Ridge located near the west end of Ahtanum Ridge.The highest point in the hills (as well as Benton County) is the Lookout Summit, which surpasses the more well-known Rattlesnake Mountain by approximately 100 ft (30 m).The Rattlesnake Hills are part of the Yakima Fold Belt of east-tending long ridges formed by the folding of Miocene Columbia River basalt flows.