United States, Illinois, Rock Island, Rock Island; W end Rock Island (Arsenal Island) NE of RR bridge at small Heliport; NE of Lock and Dam No. 15 of the Mississippi River, Rock Island Arsenal
41.516667 -90.55
41˚31’N 90˚33’W
172 meters
565 ft
Mowed area, grasses, weeds
Disturbed shallow soil on dolomite bedrock, some exposed