StainbrookGeologic Preserve - Mehaffey Bridge

The Mehaffey Bridge-Stainbrook Geologic Preserve area is an excellent location for exploration of geological forces in Iowa. Layers of sedimentary rock (to left) revealed in a road cut, indicate various periods of deposition. The fossil and shell-laden riprap that supports the duct was imported from nearby quarries and gives novice rock hounds great opportunities to find colony and individual corals, fossils, concretions and various colored rocks that reveal mineral content. Hexagonaria, horned coral, crinoids, brachiopods, chert, composites, concretions, favosites.

Stainbrook Geologic Preserve is just up the hill on the other side of the road through poison ivy and into "moraine terrain." The lay of the land causes a visitor to think it was excavated for the road. But, according to Bill Desmarais, a local geology expert, this is the remnants of glacial activity. Smack in the middle of the boggy bowl is a huge chunk of bedrock with impressive glacial grooves. What is particularly interesting and a great question to pose to students is how these grooves lay on the rock and in relation to the Cardinal Points. Some enterprising youth with a GPS on his cell phone will figure out the directions and wonder.

So a great conversation can emerge on how glaciers flow - where they come from, how they move, "tongues of glaciers", what happens when they meet resistance, the extent of their reach over the eons and episodes, land features they leave behind.



Questions: How do we know something is attached to the earth and is, thus, bedrock? Why are the low, poorly drained areas lying between Ely and Solon? Does some limestone weather better than other limestone and why? On what type structure does Mt. Mercy College lie? (Its steepest side faces the River.) How do we find the Marion Bog? What is the high point in Cedar Rapids and how high is it?

Terms: Silurian, The Wisconsin Glacial Epoch, dolomite and marble.

Directions: South on C Ave SW. East on Ely Rd. (W6E) just south of Hwy 30. East on St 382 into Solon. South to 180th Ave. on south side of town. West along 180th which becomes Mehaffey Bridge Rd. and park just before the causeway. The Cut bank is obvious on either side. Stainbrook Geologic Preserve has a little trail and takes visitors just above the road and the cut.