Bald Hill, northwest of Monroe, consists primarily of andesite flows. These blue-green porphyritic rocks weather quite readily to a light grey material with a reddish hue which can easily be disintegrated by hand. At several localities on Bald Hill vertical dikes are exposed which contain andesite xenoliths in a fine grained matrix.- Bald Hill (Snohomish County, Washington) (Wikipedia)
Bald Hill is a 737-foot (225 m) hill in Snohomish County, Washington. The Skykomish River once flowed north of the hill but at some point in recent geologic history was diverted to its present course on the south side of the hill, moving the confluence with the Snoqualmie River (creating the Snohomish River) several miles upstream. In 1952, most of Bald Hill and adjacent Devils Butte were Washington State Forest land. As of 2016, Devils Butte is part of Lord Hill Regional Park, and the Bald Hill area was still listed by Washington State Department of Natural Resources as State Forest Trust, formerly Forest Board Trust land.