Clarkia Fossil Beds Field Trip Geology 201 Spring

Clarkia Fossil Beds Field Trip Geology 201 – Spring 2009

Clarkia Fossil Beds Field Trip The Clarkia fossil beds are well known for the large number of plant species (over 100) preserved but also for the quality of preservation. Hence, the Clarkia beds represent a “Lagerstätte”; Lagerstätte” a paleontological site with significant species diversity and excellent preservation. The spring Geology 201, “Earth Through Time” class visited the Clarkia beds near Fernwood, Idaho. The class would like to thank Bill Rember for being host and guide to this spectacular Miocene locality.

Clarkia Field Trip The Clarkia beds occur in Miocene-aged (~15 million years) sediments that represent a lacustrine (lake) environment. The sediments consist of finely laminated silt and clays that have been weakly lithified. The sediments (and fossils) were deposited rapidly in a anoxic environment (deep lake? ), which led to the high quality of preservation.

Fossils of the Clarkia The vast majority of fossils found are plant species although a few fish fossils have been described. The plants are dominated by deciduous broadleaf and deciduous conifer species. Studies indicate that the paleoclimate during Clarkia time was wetter and milder than today’s climate. Clarkia climate was more like the southeastern U. S. climate of today. For more info on Clarkia fossils, go to: http: //www. uiweb. uidaho. edu/tertiary/

Bill Rember and class at the “dam site”. Here flows of the Columbia River basalts (Frenchman Springs Member, Wanapum Fm. ) dammed the local drainage forming the lake.

Dam site: pillow basalts indicating flow into water.

Bill and Ralph Granner checking out a pillow with fine-grained, “obsidian” rind.

CRB sill into “Clarkia” sediments near fossil site, Emerald Creek. Note columnar structure.

Bill Rember’s Clarkia fossil site

Interbedded ash beds (whitish) within silty clay layers.

A quick primer on separating the samples; all that is needed is a pocket knife & almost every piece contains fossils!

Leaf Removal: Bill demonstrates his leaf removal technique with HF acid. HF is a very corrosive and dangerous acid thus should be handled with extreme care.

Here between two pieces of clear plastic is the actual 15 million leaf!