DISCUSSION: Structure of the Little Badlands

Open with a description of the structures, followed by an analysis, then a discussion of previous hypotheses to explain structures, and finally list the possible origins for the structures.

Description of the structures

1. For faults or landslide blocks describe trends, types, angles of planes, features on planes, e.g. slickensides, amounts of throw of faults or landslide blocks, and age of structures)

2. For folds (axial trends, plunge amount, and age of the structures)

3. For joints (describe number and trends if you collected this information)

4. Refer to your geological map and cross-section

5. Illustrate your descriptions with photographs and drawings.

Analyze the structures

6. Are there relationships between the structures?

7. Can you summarize those relationships on a stereographic projection?

Previous hypotheses

8. Describe the contrasting hypotheses which have been used to explain the structures.

9. Do the structures have any stratigraphic depth? Does subsurface data exist which might help you answer this question?

10. Discuss the merits of each of the hypotheses (shallow folds or paleovalley) in terms of your own observations.

11. Conclude by stating which hypothesis you feel is most viable.

List the possible causes

12. Discuss how the structures may have formed. There are several possible explanations.

Useful references

Ashworth, A.C., Benton, R.C., Biek, R.F., Murphy, E.C., Shurr, G.W., Stevens, K.K., and Terry, D.O. 1996. A field guide to the Tertiary Tectonism in the northern Great Plains: road log, field trip 1. In (Paterson, C.J. And Kirchner, J.G., eds ). Guidebook To The Geology Of The Black Hills, South Dakota. South Dakota School of Mines and Technology Bulletin 19: 9-18.

Denson, Norman M., and Gill, James R., 1956, Uranium-bearing lignite and its relation to volcanic tuffs in eastern Montana and North and South Dakota. U.S. Geological Survey Prof. Paper 300, p.413-418. (Stratigraphy, map [fig. 140]).

Gerhardt, L. C., Anderson, S.B., Lefever, J.A., and Carlson, C.G. 1982. Geogical Development, Origin, and Energy Mineral resources of Williston basin, North Dakota. AAPG Bull. 66: 989-1020.

Shurr, G.W., Ashworth, A.C., Benton, R., Murphy, E.C., and Biek, R. F. 1996. Regional framework for Tertiary tectonism in the northern Great Plains. In (Paterson, C. J. And Kirchner, J. G., eds.) Guidebook To The Geology Of The Black Hills, South Dakota. South Dakota School of Mines and Technology Bulletin 19: 129-134.

Shurr, G.W., Ashworth, A.C., Burke, R.B., and Diehl, P.E. 1995. Tectonic controls on the Lodgepole play in northern Stark County, North Dakota - a perspective from surface and subsurface studies. Proceedings of the Seventh Williston Basin Symposium: Montana Geological Society Guidebook (Hunter, L.D.V., ed.,) p. 203-208.

Web sites for Rocky Mountain geology

http://hills.net:80/~misteree/Strat.html

http://wtp.net/redlodge/beartooth.htm