Lourdes Garcia, Michael Lowry, Savannah Martin, Cory Gregor
Geology 210 - Spring 2012

Introduction

On May 13th our group set out from Spokane on a 3 hour fieldtrip to visit an outcrop along the Clark Fork River near Alberton, Montana. The goal set forth was to survey the geology, collect samples, and take pictures and to research and prepare a virtual field trip. This fieldtrip was to give the geology 101 students a taste of what field work is like. Going into the trip it was known that there were very pronounced ripple marks at the Alberton site. The accepted theory regarding this formation is that they reflect the surface of the ancient Belt Sea. These ripple marks are preserved remarkably well, this is due to the lack of life thus the lack of bioturbidation. Bioturbidation is any kind of sediment disturbance or the disruption of fine sedimentary layering by digging organisms. These distinct ripple marks are shown in Figure 1.


View of the outcrop from the bridge at Alberton, Montana.

Figure 1: shows distinct ripple patterns in the lavender quartzite. This was caused by the low energy flowing water of the Belt Sea.