We head north to the Michigan-UP and south to the caves of Maquoketa
by Samantha Hayes
For the second time around, the Undergraduate Geoclub traveled to the Upper Peninsula of Michigan to explore the geology of the Keweenaw region on a warm weekend in October, this time in 2008. Two vans, nine people and a field guide (Bornhorst and Rose, 1994) set out toward Agate Beach, MI where we filled pockets and stocking hats with colorful agates. We also had the chance to go on an underground tour of Quincy Mine which allowed us to physically see the displacement caused by Hancock Fault.
We climbed and clubbed through 1085-1060 million year old geologic units of the Jacobsville Sandstone at the Natural Wall Ravine, the Portage Lake Volcanics, where we went copper hunting at the Central Mine dump pile, and finally touched the Copper Harbor Conglomerate at Horseshoe Harbor.
On November 22-23, ten members of the undergraduate geoclub and paleo club headed south towards Dubuque in search of another geologic adventure within the mysterious dolomite caverns of Maquoketa Caves State Park. The Maquoketa cave system was (re)discovered in the 1830’s and was investigated in 1980. Excavations have uncovered over 900 artifacts belonging to Late Woodland occupants between AD 300 and 1000.
As we crawled in and out of each crevasse, we came across the Hopkinton Formation and the overlying Scotch Grove Formation which were sculpted into these caves containing elaborate stalagmites and stalactites. The most memorable cave was Wye Cave, where we had to slip our way down into a sink hole surrounded by knife-like boulders. The cave opened up into a small chamber where one could stand and walk around.
Next, the group needed to crawl into a smaller shin-bashing chamber that led to an eleven inch thick “squeeze” (rightfully named). Fortunately, the squeeze was less than ten feet long until the cave once again opened up into a larger room. As you can tell, our group definitely got “down and dirty” for this trip. The fossils seen were crinoid molds (sea lilies) of the phylum, echinoderm. One of our members even found a partial body fossil of a trilobite (early Cambrian arthropods) along a roadside mining pile. We used the GSI Guidebook by Anderson (2001) along with the previous Maquoketa caving experiences of UW students, George Rothdrake and Lisa Lesar.
These trips gave our participants a better understanding about the structure, mineralogy, sedimentology, glacial geology, and even the human history of the world under our feet. I personally would like to thank UW graduate student, Jason Huberty, for being our guide during the Keweenaw trip. His knowledge of the area enhanced our educational experience of UP-Michigan.
The UW Undergrad Geoclub and Paleontology Club would like to thank members and alumni of the department for their generous support of undergraduate field trips.
Originally published in The Outcrop for 2008, UW-Madison Department of Geology and Geophysics, p. 11.