We are thrilled that our members are eager to share photos and descriptions of outcrops they know and love. Welcome to an interview with Nuri Uzunlar of South Dakota School of Mines as he shares a few of his favorites.

Please describe your favorite outcrop. Where is it? What is it? What makes it so special?

Outcrop in the Black Hills of South Dakota. Located behind Lead High School, next to Homestake Gold Mine

That’s an impossible question. To me, it isn’t about how outcrops look, but rather the story that they tell. Some outcrops cover billions of years of geologic history, and others register and preserve major events. I’ll only list two of my favorites.

Black Hills of South Dakota

One of my favorites in the Black Hills and it has a big story to tell. Here, the Deadwood Formation (550Ma), named after the town of Deadwood, the type locality, about a mile north of here, rests on 1.8Ga Proterozoic schist (lower level, lavender colored). The conglomerate layer at the base of the Deadwood Formation (semi horizontal beds) gives all the erosional history of the Black Hills during the Cambrian period. Students picture the 1.2 Ga geologic gap at this nonconformity and learn about characteristics of the Cambrian seas.

This outcrop is located near the town of Taskesti in Turkey’s Bolu Province. It’s one of the Turkey field camp’s projects.

Taskesti, Turkey

It’s been said that the story of the mountains is written in its basins and this outcrop in Turkey is a real example of that. Students spend a day learning many aspects of geology just by studying this 20 meter section. This roadcut offers so much information – from the closing of Tethys to the nature of the magmatic arc feeding detrital materials to this channel on the edge of an upper Jurassic basin. It offers many other features, such as submarine avalanches to soft sediment deformation to small scale faulting. One could write a dissertation from this small road cut.

Are there other outcrops that you particularly like? Please describe them briefly.

This outcrop is from the Cotopaxi volcano in Ecuador.

Cotopaxi, Ecuador

This outcrop in Ecuador is also a field camp project, mapping a variety of lavas of volcan Cotopaxi. This spectacular unconformity is located a few miles south of the volcano along the road displaying multiple layers of volcanic ash and lava and a picture-perfect display of angular unconformity.

There are too many outcrops to list, but here are a few more with short descriptions.

I will never forget the outcrop in one of the parking lots on the big island of Hawaii where many mantle xenoliths were cut up in the rising basaltic magma, preserved perfectly, and displayed colorfully. Another outcrop is again in Turkey near the town Mihallicik, north of Eskisehir Province. Here on the Tethyan suture zone, the blue schist outcrops are so fresh – as if they just completed their exhumation journey from 80km depth. I should also mention a few outcrops with vibrant colors in Landmannalaugar’s multicolored summit of Mt. Brennisteinsalda. There are many others in the High Atlas - Morocco, the Alps in southern France, and the Pyrenees range in Spain.