Question

Gaining Insight into Depositional Environments of Sedimentary Rocks

Answer 1

Answer:

(a): 7. and 8.

(b): 6.

(c): 9.

(d): 4.

(e): 10

(f): 1.  

(g): 2.  

(h): 5.  and 3.  

Explanation:

Sedimentary rocks are rocks generated from pre-existing rocks and/or once-living organisms. Arkose is a type of sandstone rich in feldspar (at least 25% of this mineral). Moreover, a rock containing coral fossils indicates that its depositional environment was located in warm tropical reef waters. Mudstone is a kind of sedimentary rock composed of clay (in this case, sediments continued to be deposited above the dinosaur footprints). The black shales are fine-grained sedimentary rocks composed of a mixture of clay (in this case, the pyrite crystals are used as an indicator of low oxygen). Symmetrical ripple marks in the sandstone indicate a marine environment where water motion was dominated by wave oscillations. Cross-bedding is a common structure of sedimentary rocks that form during deposition on inclined surfaces of bedforms (e.g., ripples and dunes). Sediment deposition in swamps is usually heavily vegetated and therefore they are rich in organic matter, while deeper swamp sediments are generally anoxic. Finally, cobblestones are naturally occurring cobble-sized stones formed from the flow of water and gathered from stream beds, while pebblestones are formed when water bodies hit the giant rocks in the rivers and lakes.