The following papers will help you to understand the different geological interpretations that have been applied to the Little Badlands.  As you read these papers, you might want to construct a table in which you list the expected differences between faults and landslides.  Some criteria might be: morphology of the surface trace of the structure, curvature of the slip plane, features on the slip plane such as slickensides or lineations, competence of the strata, angular relationships of the strata, etc.
 

Gill, J.R., 1962, Tertiary landslides, northwestern South dakota and southeastern Montana. Geological Society of America Bulletin, 73: 725-736.   (Provides a model for the origin of pre-Miocene structures in the Slim Buttes, South Dakota - NDSU Library 550.5 G29)

Denson, N. M. and Gill, J. R. 1965. Uranium-bearing lignite and carbonaceous shale in the southwestern part of the Williston Basin - a regional study. Geological Survey Professional Paper 463, 75 p. with maps, US Government printing Office, Washington, D. C. (Provides a structural interpretation for the geology of the Little Badlands)

Hickey, L. J. 1977. Stratigraphy and paleobotany of the Golden Valley Formation (Early Tertiary) of western North Dakota. Memoir 150, Geological Society of America (Provides useful information on the stratigraphy and sedimentology of the Golden Valley Formation)..

Murphy, E.C., Hoganson, J.W., and Forsman, N.F. 1993. The Chadron, Brule, and Arikaree Formations in North Dakota. Report of Investigation No. 96, North Dakota Geological Survey (Good overview of the geology of the Little Badlands, especially stratigraphic units)

Seeland, D. 1985. Oligocene paleogeography of the northern Great Plains and adjacent mountains, In ( Flores, R.M. and Kaplan, S.S., eds.) Cenozoic Paleogeography of west central United States. pp. 187- 205. SEPM, Rocky Mountain section (Sedimentological -tectonic interpretation of the White River Group).

Stone, W. J. Stratigraphy and Sedimentology of middle cenozoic (Oligocene and Miocene) deposits of North Dakota. 1973. Ph.D. Thesis, University of North Dakota (Provides a sedimentological and structural interpretation for the deposits of the Little Badlands that conflicts with the Denson and Gyll hypothesis).

The following maps, book chapters and papers provide useful background information

Field methods, symbols and notations

Compton, R.R. 1985. Geology in the Field. Wiley, 398p. (Use of the compass pp.16-20; basic procedures at outcrops, taking notes, measuring strike and dip, etc, pp. 22-40;finding and tracing contacts between rock units, pp. 80-83; Measuring and describing stratigraphic sections, pp. 222-241; Illustrations for reports, cross-sections, etc.pp. 348-353).

Dutro, J.T., Jr., Dietrich, R.V., and Foose, R.M. 1989 AGI Data Sheets for Geology in the field, laboratory, and office, Third Edition. American Geological Institute (Geologic map symbols -sheets 3.1, 3.2, 3.3,3.4,3.5; Symbols for fluvial nonmarine sequences - sheet 4.1; US Public Land Survey Grid - sheets 5.1, 5.2)

Sedimentology - Read about facies and sedimentary structures of  fluvial and deltaic systems. Several potential sources including:

Boggs, S., Jr., 1995.  Principles of Sedimentology and Stratigraphy.  Prentice-Hall. (Chapter 5, Bedding pp. 108-131; Chapter 10, Continental Environments, pp. 299-318).

Davis, R. A., Jr., 1992.  Depositional Systems. Prentice-Hall. (Chapter 3, Sedimentary Structures, pp. 60-75); Chapter 7, The Fluvial System, pp. 204-237).

Prothero, D. R. and Schwab, F.  1996. Sedimentary Geology.  Freeman (Chapter 4 - Sedimentary Structures, pp. 43-52); Chapter 8 - Terrestrial Sedimentary Environments, pp. 137-157)

Walker, R. G. 1984. Facies Models. Geoscience Canada Reprint Series 1, 317 p. ( Consult sections on alluvial fans, sandy fluvial deposits , and deltas). Especially important to know how the facies of a meandering system differ from those of a braided system).

Structure - Read about methods for analyzing and plotting structures, especially normal faulting.  There are several potential sources, including:

Davis, G. H. and Reynolds, S.J., 1996.  Structural Geology of Rocks and Regions. John Wiley &  Sons, Inc. (Measuring structural orientations with a compass (pp. 662-669); Preparing Geologic Cross Sections (pp. 669-674); Stereographic Projection (pp. 691-720); Methods in Joint Analysis (720 - 730); Normal Faulting (340-352).