Blue Hole (New Jersey)
The Blue Hole is located in the Pinelands of Monroe Township, Gloucester County, New Jersey and Winslow Township, Camden County, New Jersey. It is a clear blue body of water situated in the middle of a dense forest, with many similar such lakes in its immediate vicinity. The water has warm and cold spots, averaging 58 to 60 degrees Fahrenheit. The color is very unusual, as most lakes and ponds in the area are brownish due to large deposits of bog iron and the presence of tannic acid. The Blue Hole is circular and about across. In the 1930s, the Blue Hole was a popular party and swimming spot. A wooden footbridge over the Great Egg Harbor River that once made the Hole easily accessible was wiped out by a storm in the 1960s; now it can only be reached on foot.
Blue Hills (Washington)
The Blue Hills are perched on the north edge of the Seattle uplift, an east-west trending syncline or arch between the Seattle Fault and Tacoma fault formed by north-south compression of the bedrock. (See Puget Sound faults#Geological setting.)
Sharp downwarping of these formations has created numerous faults, including the dip-slip (vertical movement) Gold Creek fault that separates the two mountains. Strands of the Seattle fault, which east of here trend nearly due west-east, appear to turn to the southwest in the vicinity of Green Mountain.