The Rock Cycle is a circle of changes. Igneous rock can change into sedimentary rock or into metamorphic rock. Sedimentary rock can change into metamorphic rock or into igneous rock. Metamorphic rock can change into igneous or sedimentary rock. It is not very often that all three rock types are visible in a single location.
Logging Requirements: To log this EarthCache, please examine the rocks on the slope to the beach, in particular the following three features. Answer the questions and comment on the condition of the rocks in the rock cycle.
-the sand coloured rocks near the top of the slope.
-the grey/black coloured rocks near the bottom of the slope.
-the pink rocks in the middle of the slope.
Based on the descriptions below, which feature is a sedimentary limestone (coarse texture), a metamorphic schist (fine layered crystals), an igneous granite (visible crystals light colored quartz and feldspar)?
Comment on each rock feature as follows.
Is this a sedimentary, an igneous, or a metamorphic rock?
a. if sedimentary, which type: clastic, chemical, or organic.
b. if igneous, which type: intrusive or extrusive.
c. if metamorphic, foliated or non-foliated.
Sedimentary rocks are formed by the accumulation, compaction and cemetation of sediments. There are three basic types of sedimentary rocks:
-clastic sedimentary rocks such as breccia, conglomerate, sandstone and shale, that are formed from mechanical weathering debris;
-chemical sedimentary rocks such as rock salt and some limestones, that form when dissolved materials precipitate from solution;
-organic sedimentary rocks such as coal and some limestones which form from the accumulation of plant or animal debris.
Igneous rocks are formed from the solidification of molten rock material. There are two basic types:
-intrusive (meaning: "under the surface") igneous rocks such as diorite, gabbro, granite and pegmatite that solidify below Earth's surface. Intrusive rocks cool slowly and have coarse grained crystals.
-extrusive (meaning: "above the surface") igneous rocks such as andesite, basalt, obsidian, pumice, rhyolite and scoria that solidify on or above Earth's surface. Extrusive igneous rocks generally cool quickly and have fine-grained crystals.
Metamorphic rocks have been modified by heat, pressure and chemical process usually while buried deep below Earth's surface. Exposure to these extreme conditions has altered the mineralogy, texture and chemical composition of the rocks. There are two basic types of metamorphic rocks:
-foliated or layered metamorphic rocks such as gneiss, phyllite, schist and slate which have a layered or banded appearance that is produced by exposure to heat and directed pressure;
-non-foliated metamorphic rocks such as marble and quartzite which do not have a layered or banded appearance.
