Tuesday, March 2nd, 1999

Announcements: Professor Furman will try to return all writing assignments by the Thursday lecture after spring break.

Lecture notes:

I. Preview
    A. "Surface Processes" -- things that go on at the surface of the earth
            1. Weather--what is occurring at a particular moment in any given area (ex. rain, snow, sleet, high temperatures)

            2. Climate--the average temperature, precipitation, barometric pressure, etc. in an area; it is influenced by
                geography and topography

            3. Weathering--two types of weathering
                    a. Chemical weathering--the making of little pieces from big pieces
                            (1). Hydrolysis--chemical breaking apart of rock by water; gradual replacement of unstable materials
                                    by stable ones
                            (2). Acid-enhanced--a little faster today than in earlier years; any acid speeds up the process of
                                    weathering

                    b. Mechanical weathering (physical weathering)--the making of new types of materials that were not
                        there previously
                            (1). Physical break-up of rock; needs water because it is the only compound that has a change in
                                    volume when it freezes and therefore forces and splits apart rock in low temperatures
                            (2). Crack expansion caused by plants and roots; roots split the rock apart

            4. Mass transport

            5. Rivers
 
            6. Deltas

    B. Sediments
            1. Generation (erosion, weathering)

            2. Transport

            3. Deposition

            4. Lithification (rock formation)

            5. Most abundant mineral on earth is Feldspar
 
II. Badlands (South Dakota, east of the Rockies)
    A. Young Rockies
            1. About 30 million years ago sediments deposited on route to the Mississippi

    B. Younger Rockies (2-10 million years ago)
            1. Earlier sediments stripped away

    C. Slides
            1. Can tell mountains are young because the layers are flat, not bent, tilted, etc. meaning there has been no
                pushing, faulting, or moving of material there yet

     D. Sediments of Badlands are primarily clay
            3. "Types of clay and volcanic ashes in the Badlands, combined with the climate in which they now occur,
                are not the sort that make good, fertile, stable soils" (Alley 62).

             2. "The clays expand and shrink on wetting and drying, contributing to the instability of the steep slopes
                 that causes them to remain unvegetated" (Alley 62).

    E. Badlands are a large, region of very low slope