Sedimentation & Stratigraphy (89.352)

Sedimentation & Stratigraphy (89.352) http://faculty.uml.edu/lweeden/SedStrat.htm

Brief History of Sedimentation and Stratigraphy Nicolas Steno (1638 – 1686) Principles of Superposition and Original Horizontality. James Hutton (1727 – 1797) Principle of Uniformitarianism (aka. Actualism) William “Strata” Smith (1769 – 1839) Law of Faunal Succession. Johannes Walther (1860 – 1937) Walther’s Law of succession of facies

Chapter 1: Weathering and Soils • I. Physical Weathering • . Freeze – Thaw (Frost Wedging) • . Insolation Weathering • . Salt Weathering • . Wetting & Drying Weathering • . Stress Release Weathering • . Other Physical Process • How does surface area contribute to weathering processes?

Frost Wedging

Insolation Weathering (Spalling)

Salt Weathering

Wetting and Drying Weathering

Stress – Release Weathering

II. Chemical Weathering (Table 1.1) • . Simple Solution • . Hydrolysis • . Oxidation / Reduction • . Hydration / Dehydration • . Ion Exchange • . Chelation

III. Weathering Rates • There is no mathematical solution to precise weathering rates. It is all relative…. • . Climate (physical - cold and dry; chemical – hot and wet.) • . Stability of Minerals “Happiness Principle” Table 1.2 • . Subaerial Weathering (Table 1.3) • . Submarine Weathering • .Halmyrolysis 2.Magnitude of Circulation and effects.

Physical weathering dominates in cold and dry climates. Chemical weathering dominates in warm and wet climates.

Stability of Minerals and “The Happiness Principle”

Order of increasing “weatherability”

Table 1.2

Subaerial Weathering (Table 1.3)

Submarine Weathering and Halmyrolysis

IV. Soils • . Soil is a product of bedrock weathering. • . The thickness and characteristics of a soil is a function of: • . Bedrock lithology • . Slope of bedrock surface • . Climate • . Biological activity • . Additions to ground surface • . Transformation • . Transfers • . Removals • . Bioturbation of Soils

Soil-Forming Processes 1. Additions to the ground surface—Precipitation of dissolved ions in rainwater; influx of solid particles (dust, etc.); addition of organic matter from surface vegetation (leaf litter, etc .) 2. Transformations a. Decomposition of organic matter with soils to produce organic compounds. b. Weathering of primary minerals; formation of secondary minerals, including iron oxides. 3. Transfers a. Movement of solid or suspended material downward from one soil horizon to a lower horizon by groundwater percolation (eluviation) b. Accumulation of soluble or suspended material in a lower horizon (illuviation) c. Transfer of ions upward by capillary movement of water and precipitation of ions in the soil profile

Soil forming processes continued… 4. Removals—Removal of substances still in solution to become part of the dissolved constituents in groundwater or surface water 5. Bioturbation of soil—Soil disrupted by animals (i.e. ants and termites) and plants.

G.Soil Profile Bedrock

Water enters system Minerals leached Altered minerals accumulated with different chemistry than original material

Gelisols Histosols Spodosols Andisols Oxisols Vertisols Aridisols Ultisols Mollisols Alfisols Inceptisols Entisols H. Soil Classification (Taxonomy)

Review climatic effects of soil formation.

I. Paleosols—ancient soils, fossil soils or soils that escaped the effects of erosion to become part of the sedimentary record.

Recognition of Paleosoils –Glaebules, Mottles & Burrows…Oh my!

See Figure 1.6 of Text

Sedimentation & Stratigraphy (89.352)