12 depositional sedimentary environments lab | Geology homework help

24. How does a conglomerate form? Is there more than one way? If so how?

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Laboratory 12: Sedimentary Depositional Environments (Macro Scale) Objective:

To understand the large sale features that are observed in sedimentary environments and the role they play in understanding depositional environment. Materials Needed: Images of various sedimentary environments provided by instructor Paleogeography is the study of what an environment was like during a certain time in the past. Paleogeography takes biostratigraphy one step further in reconstructing the earth's history. By examining a set of rocks in several different locations, all representing the same age, we can begin to reconstruct the ancient environment by using the rock type and fossil content. The rock samples can be collected over a large or small lateral area, and the locations and shapes of landmasses and seas can be deduced by knowing which types of rocks and fossils are expected to be found in particular environments. An environment of deposition is the sum of all physical, geographic, climatic, ecological, and chemical parameters that affect the composition of the sediment. Many factors must be considered when deciding on the environment of deposition, including lithology, fossil abundance, and fossil assemblage. I. NONMARINE (CONTINENTAL) Most non-marine environments are typically the sites of erosion or non- deposition, although a small percentage of deposits may be preserved. A. Aqueous- 1. Fluvial (streams and rivers)- (a) Floodplain- Sandstone, siltstone and shale with some conglomerate and coal, moderate sorting, moderately quartz-rich; horizontal laminations, asymmetric (current) ripple marks, animal tracks and trails, mud cracks, raindrop impressions; plant debris and tree fossils; irregular and thin sheet shape. (b) Channel-Sandstone and conglomerate, moderately sorted and quartz-rich; cross-bedding, current ripple marks, scour of channel surfaces; may contain plant debris, non-marine (aqueous and terrestrial) fossils; irregular lenticular to sinuous shape, closely associated with floodplain deposits.