The following stops are directly pertinent to the assigned cross-section and questions:

Michael A. Stewart, Ph.D.Department of Geology, School of Earth, Society and Environment, College of Liberal Arts and Sciences, University of Illinois at Urbana-Champaign

A Cross-Section and Geologic History from Field Data Collected by Second Year Students in the St Francois Mountains of Missouri

Acknowledgments

My participation in this workshop was generously funded by the Provost’s office of the University of Illinois, and the Geology Department in the School of Earth, Society and the Environment in the College of Liberal Arts and Sciences at the University of Illinois

Rational:

Often Geology students complete their degrees with little practical field experience beyond what they obtain at Field Camp. This exercise introduces students to field projects early in their studies.

The University of Illinois Geology Department does not have a field methods class. Rather, each core course has a field trip as a significant component to the class. This field trip is their second such trip, and the first with project-based work.

I intend for my students to arrive at Field Camp (and thus complete their degree) with significant experience collecting field data with the purpose of producing field-based project work.

Purpose: 

To introduce second year Geology Majors to field based projects

This introduction occurs while our Earth System History class takes a three-day field trip to St. Francois Mountains of eastern Missouri. 

The Project Assignment

Given• Topographic map of the field area• Cross-Section line indicated on the map• Field trip stop locations on the map 

Topographic map of the field area with cross-section line indicated.

At each outcrop, the context is discussed so the students are able to assemble a basic geologic history of the area.

During the evenings of the trip and after we return to campus, students work to…

Complete a topographic profile of the cross-section line

Complete the cross-section and legend

Turn in their field notebook

Answer the following questions:

• What is the vertical exaggeration of your cross-section?

• What is the relative age of the granite outcropping at Elephant Rock SP compared to the ignimbrite flows exposed along highway 21?

• What is the geologic setting/environment during deposition of the Cambrian aged Lamotte Sandstone?

The Assignment:

At a series of natural outcrops and road-cut exposures, students

Write rock descriptions of the various rock types

Observe and interpret primary textures and structures in the rocks and outcrops.

Reason out field relationships between units

Are shown how to collect strike and dip of bedding surfaces

Sketch outcrops illustrating field relationships

The Activity: Cross Section and Associated Questions

Stop 7A road-cut exposes a Paleo-Proterozoic ignimbrite (welded lapilli-tuff) with a paleo regolith at its upper surface, the regolith is overlain by a basal breccia of the Lamotte Sandstone. 

Stop 5Paleo-Proterozoic granite

Stop 4b  Paleo-Proterozoic ignimbrite (crystal tuff) with no obvious internal structure. Perhaps alignment of phenocrysts suggest inclined from original horizontal.

Stop 4aPaleo-Proterozoic ignimbrite (welded crystal lapilli-tuff) with abundant fiamme (>1 inch) indicating inclination from original horizontal. Two flows preserved at this location, separated by a flow breccia.

Magnified for presentation and no longer to scale of the map