Rocks, resources and scenery

geological timescale- the period of geological time since life came abundant millions of years ago, divided into eras and periods
the periods are smaller than eras
igneous rock- formed by the cooling of magma(extrusion or intrusion) forms small and large crystals e.g.granite
sedimentary rock- formed by accumulation of sediment on sea floor under immense pressure and heat e.g. sandstone
metamorphic rock- rocks that have undergone change in their chemistry due to heat or pressure formed by previous sedimentary or igneous rock e.g. slate
GRANITE-formed 280 mill years ago
CARBONIFEROUS LIMESTONE- formed 340mill years ago
CHALK- formed during cretaceous period
CLAY- formed during cretaceous and jurassic period

rock cycle- 1) igneous rock broken down by weathering and transported to sea as sediment 2)deposition of sediment on sea bed forms layers and creates sedimentary rock by pressure 3) the sedimentary rock is put under extreme heat forming metamorphic rock 4)metamorphic rock is melted to form magma and crystalised either extrusively of intrusivley to form igneous rock

Weathering- disintergration or decay of rock in their original place at or close to the ground surface
BIOLOGICAL- caused by living organisms such as tree roots creating cracks in rocks and animals burrowing into soft rocks
CHEMICAL- involves a chemical change taking place for example acid rain weathering away to create a limestone pavement
MECHANICAL- does not involve chemical change only physical break up of rocks for example freeze thaw weathering
freeze thaw weathering occurs when the water finds its way into cracks or joints, at night temperatures drop so the water freezes and expands: windening the crack. During the day the water melts and at night the process is repeated again until rock fragment breaks off and collects at the foot of the rock face as scree (MECHANICAL)
exfoliation occurs mostly in places like the dessert when temperatures fluctuate because the skin of the rock expands during the hot temperatures in the day and then it contracts during the cold temperatures at night- this repeated process can lead too the skin peeling away from the rock. The presence of water is involved to weaken it and make it more vulnerable to flaking. (MECHANICAL)
Solution is the dissolving of rocks or minerals…

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