Green Rock, Illinois, technically no longer exists. The town itself has been assumed into the town of Colona, Illinois. Green Rock was named so because it is the place where the Green River meets up with the Rock River. Colona is a city located in Henry County, Illinois. ... Green River may refer to: // Rivers Canada Green River in New Brunswick. ... Rock River may refer to: the Rock River, a tributary of the Mississippi River in Wisconsin and Illinois in the United States the Rock River, a tributary of the Big Sioux River in Minnesota and Iowa in the United States any of three Rock Rivers in Michigan in the United...