sedimentary rock classification

types of sedimentary rocks

Rock Conglomerate Breccia Sandstone Siltstone Shale Sediment Size Large Large Sand-sized Silt-sized, smaller than sand Clay-sized, smallest Other Features Rounded Angular When sediments settle out of calmer water, they form horizontal layers. One layer is deposited first, and another layer is deposited on top of it. So each layer is younger than the layer beneath it. When the sediments harden, the layers are preserved. Sedimentary rocks formed by the crystallization of chemical precipitates are called chemical sedimentary rocks. As discussed in the concepts on minerals, dissolved ions in fluids precipitate out of the fluid and settle out, just like the halite in Figure 1.1. The evaporite, halite, on a cobble from the Dead Sea, Israel. Biochemical sedimentary rocks form in the ocean or a salt lake. Living creatures remove ions, such as calcium, magnesium, and potassium, from the water to make shells or soft tissue. When the organism dies, it sinks to the ocean floor to become a biochemical sediment, which may then become compacted and cemented into solid rock (Figure 1.2). Table 1.2 shows some common types of sedimentary rocks. Breccia Clastic Sandstone Clastic Siltstone Clastic Shale Clastic Rock Salt Chemical precipitate Dolostone Chemical precipitate Limestone Bioclastic (sediments from organic materials, or plant or animal re- mains) Coal Organic Click image to the left or use the URL below. URL:



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conglomerate rocks are made from

a) jagged, angular rocks

-->  b) round rocks

c) sand

d) clay

shale is made from

a) jagged, angular rocks

b) round rocks

c) sand

-->  d) clay

biochemical sedimentary rocks from in oceans or salt lakes.

-->  a) true

b) false

which of these rocks are not clastic?

a) conglomerate

b) sandstone

-->  c) coal

d) shale

sedimentary rocks in order of particle size from small to large is

a) conglomerate or breccia-sandstone-siltstone-shale.

-->  b) shale-siltstone-sandstone-conglomerate or breccia.

c) sandstone-shale-breccia-siltstone-conglomerate.

d) sandstone-siltstone-shale-conglomerate-breccia.

rock salt is a clastic rock.

a) true

-->  b) false

sediments are deposited

-->  a) horizontally

b) vertically

c) as a coating on the land surface

d) all of these

sedimentary rocks are made by

a) rock fragments

b) precipitate from fluids

c) precipitation from living organisms

-->  d) all of the above

which of these rocks forms from chemicals that precipitate from evaporating water?

a) rock salt

b) coal

-->  c) gypsum

d) conglomerate

sedimentary rocks are classified by

a) how they form.

b) sediment size.

c) whether they are made from living things.

-->  d) all of the above.

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