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Karteikarten von Fatima Waseem, aktualisiert more than 1 year ago
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Erstellt von Fatima Waseem
vor mehr als 6 Jahre
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| Frage | Antworten |
| 8.3 Sedimentary Rocks | rtkjhfidu7f987srf9uifudif |
| what are sedimentary Rocks? | Rocks that are made from sediments. |
| what are sediments? | small particles of broken down rock due to weathering |
| How are sedimentary rocks formed? | 1)sediments are compacted and cemented 2) The overlaying layers of rock force out excess water 3)the the chemicals in groundwater cement the sediments together |
| What are the 3 types of sedimentary rocks? | 1) Clastic 2) Chemical 3) Biogenic |
| How are Clastic Sedimentary rocks formed? | They are formed when sediments are laid down by water, wind, ice and gravity then compacted and cemented |
| What are the characteristics of Clastic Sedimentary rocks? | 1)They contain broken pieces of other rock 2)They may have layers 3) Grains don't interlock 4) they rock may contain fossils |
| How are Clastic Sedimentary Rocks classified? | According to their size, the nature of the rock grains and chemical composition of the cement |
| What are some different types of Clastic Sedimentary Rocks? | 1)Conglomerate 2)Mudstone 3)Breccia 4)Sandstone |
| Describe conglomerate | Large rounded rocks cemented between grains the are often microscopic |
| Describe Mudstone | Particles often microscopic, very soft rock |
| Describe Breccia | similar to conglomerate but lumps are sharp-edged |
| Describe sandstone | Particles of sand, usually harder than mudstone |
| How are Chemical Sedimentary rocks formed? | When minerals dissolve in groundwater and crystallise within the sediments or when water evaporates, leaving behaind crystals |
| What are the characteristics of Chemical Sedimentary rocks | Quite soft crystals, and this helps to distinguish them from the much harder igneous rocks. |
| What are some examples of Chemical Sedimentary Rocks? | 1)Halite 2)gypsum 3)limestone |
| How are biogenic Sedimentary rocks formed? | When dead palnt matter or animal remains accumulate and are then cemented together |
| What are the characteristics of Biogenic Sedimentary rocks? | Can be layered and are usually soft, although a few such as chert and flint can be fairly hard |
| What is strata? |
layers of sedimentary rocks
Image:
Strata (binary/octet-stream)
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| How do we determine which layer is younger and which is older | the bottom layer is the oldest, the top layer is the youngest |
| What is an example of a Biogenic Sedimentary rock? | Coal |
| What are fossils? | The preserved evidence of oranisms that once existed of earth |
| Why cant soft parts of organisms be preserved? | soft parts of organisms decay much faster than hard parts, get eaten by other organisms or get weathered away |
| What are the most commonly found fossils? | skeletons,teeth, shells or wood |
| what are the conditions that preserve an organism? | 1) the remains need to be quickly covered by sediments so they dont get eaten, weathered away or decayed 2) Oxygen needs to be sucked out of the organism |
| What is relative rock? | its not the actual age of the rock but only indicated that if it is older or younger from another rock |
| How do you determine the older rock if they are both in one location? | By their position in the rock strata, the deeper the older |
| What does a index fossil have to be? | 1) be found over a wide spread area 2) Have lived in a narrow period of time in the past 3)have been abundant with lots of oraganims living at the time |
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