GEOL 1001 Chapter : Chapter 5 Outline Test 2
Document Summary
6. 13: crosse beds- created by ripple and dune migration, sediment moves up the gentle side of a ripple or dune, then slips down the steep face. Indicate the direction of water or air current: ripples, dunes- similar to ripples except much larger, forms from wind-blown sand in desert or beach regions, often preserves large internal cross-beds graded bedding (fig. Differ in : energy regime, sediment deliver, transport, and depositional conditions, chemical, physical and biological characteristics, environments range from continental to marine. Ice carries and deposits every grain size: mountain streams. Mountain streams: water carries large clasts during floods, during low flow, these cobbles and boulders are immobile. Sand dunes- wind-blown piles of well-sorted sand: arid regions, result is uniform, cross-bedded sandstones. Fine sand, silt, and clay are deposited on nearby floodplains. Deltas-sediments dropped where a river enters the sea. Sediment carried by the river is dumped when velocity drops.
