In November of 2008 I had the pleasure of going on a field trip to Arkansas as part of an undergraduate mineralogy course. We camped at Lake Ouachita State Park near Hot Springs. This area is a great place to find a variety of minerals thanks to the Ouachita Orogeny and the Magnet Cove ring-dike intrusion. It’s also a great place to have your food stolen by animals.
The Ouachita Orogeny was a mountain-building event caused by a collision between North and South America around 300 million years ago. Over millions of years the pressure of the colliding tectonic plates caused intense folding and faulting of the sedimentary rocks and the uplift of the Ouachita Mountains. Many fractures that formed in the rock were flooded with mineral-rich water, allowing for the formation of large euhedral crystals of quartz.
The Magnet Cove ring dike intrusion occurred later, around 90 million years ago. Here magma from the earth’s mantle ascended and melted its way up into the crust, but never reached the surface. The intense heat and unique chemical elements contained in the magma helped form some of the interesting minerals beneath the surface.
Since then the Ouachita Mountains have been eroding for tens of millions of years, and many of the minerals formed by these two geologic events have been exposed at the surface. While there are many locations to search and minerals to be found, here are some highlights:
After long days of driving and hiking to these various destinations, hunting for mineral samples, and answering field questions, the evenings were a welcome break in the action. We spent the nights crowded around a campfire (it got below freezing), telling stories, and asking questions. Unfortunately after it gets dark and you get tired you tend to forget small details, like making sure the cooler full of meat is latched shut. Scavengers from opossums (Didelphis virginiana, Didelphidae) to raccoons (Procyon lotor, Procyonidae) to even black bears (Ursus americanus, Ursidae) roam at night, seeking the prized foodstuffs of campers. I awoke one morning to find our cooler pilfered by one such scavenger:
At least it was probably only a raccoon. A black bear might have made for a more interesting night.
Camping tip: Stick some food in the bottom of a friend’s sleeping bag. Hilarity will ensure. Or death. But probably only hilarity. Or nothing. It’s worth a shot though.