Announcements Field trip this Friday—8:15 am gone by 8:30 – Bring all your field supplies and handouts hand lens, mapboard, field notebook, description guides, camera, trowel, etc. – Lunch, warm layers, sturdy shoes – drivers: Emily (4), Sarah (5) This week: Descriptions and reading questions due Thurs. at start of class New activity: Sediments on the Move! & Completed field guide to movies

Sed. descriptions (not interpretations... yet!) Color indicates: mineralogy (framework, matrix, cement, weathering products) darkness indicates organic content (carbon) available oxygen during deposition (ex. clay in red chert oxidizes during settling) available oxygen during diagenesis, composition of pore waters, porosity due to grain size

Sediment descriptions Composition indicates: source area, leading to interpretations for tectonic setting, weathering and climate characteristics Texture (size/sorting, shape/roundness, texture) distance from source, possible recycling transporting agent, depositional process, diagenetic effects – ex. setting, saltating, or traction Fabric sedimentary structures give info on type / nature of flow including velocity, geometry / extent, time period

churning of sediments by critters – destroys original fabric and sedimentary structures changes permeability pathways (how water & oxygen enters) changes biochemistry due to consumption / byproducts oxidation color can be mottled by organic materials affecting pH (reduction spots) Bioturbation

Dissolution changes shape of grains – Solubility changes with depth: SiO 3 increases, CaCO 3 decreases (unless high CO 2 due to decomposition of organic matter) Chemical compaction can cause stylolites from dissolution Alteration seritization alters feldspars to clay volcanics can appear significantly oxidized carbonates replaced by silica glauconite may grow (marine secondary mineral) Diagenesis

Compaction burial reduces porosity squishes grains (flattened) and thins beds can create pseudomatrix Cementation fluids from dissolution (during compaction) or introduction may be multiple stages (e.g., during burial, subsequent uplift) overgrowths obscure original grain shape concretions, nodules, leisegangen banding may obscure fabric Diagenesis

Question 1: Laminar vs. turbulent flow define two terms list conditions Re = vL/ν where ν = kinematic viscosity

Question 1: Laminar vs. turbulent flow Re = vL/ν where v = velocity ν = kinematic viscosity

Question 2: Viscosity effects Compare the viscosity of ice, air, liquid water explain medium’s tendency toward laminar or turbulent flow how does viscosity affect the ability of each medium to transport sediments? – RE# = vL/ν

Question 3: Density vs. viscosity What is the difference between density and viscosity? Compare the density of air and liquid water

Question 3: Density vs. viscosity What is the difference between density and viscosity? – consider oil and water! Compare the density of air and liquid water – density air = g / cm³ – density water = 1 g/ml

Question 3: Density vs. viscosity

The Bernoulli Effect