Essay on The Science of Rocks
1.According to Thompson and Turk (2011), there are two types of igneous rocks
extrusive and intrusive and the primary difference between the two types of
igneous rocks is that the rocks are formed in two separate locations: within the
Earth s crust and on the Earth s surface (35). Extrusive igneous rocks form when
magma rises all the way through the crust to erupt onto Earth s surface (35). Since
the crystals do not have much time to grow, extrusive sedimentary rocks, also
commonly known as volcanic rocks, have fine grained textures, with crystals too
small to be seen with the naked eye (Thompson Turk, 2011, 36). For example, basalt
is a common very fine grained volcanic rock. On the other hand, intrusive igneous
rocks form when... Show more content on Helpwriting.net ...
The difference in the mineral composition is apparent in the rocks color and grain
texture. Since basalt is a mafic rock, it tends to have a dark green to black, dark
color, while granite tends to have a clear, white, and pink light color (Thompson
Turk, 2011, 37). Additionally, because basalt is an extrusive igneous rock, it has a
very fine grained texture, meaning that the crystals are nearly impossible to see
(Thompson Turk, 2011, 36). On the other hand, granite is an intrusive igneous rock,
meaning that it has a medium or coarse grained texture, where the mineral grains and
crystals are easily visible (Thompson Turk, 2011, 36).
3.According to Thompson and Turk (2011), sedimentary rocks are broadly divided
into four categories: clastic, organic, chemical, and bioclastic rocks. Clastic
sedimentary rock is composed of particles of weathered rocks, such as sand grains
and pebbles (also known as clasts), which have been transported, deposited, and
lithified (38). Clastic rocks, such as shale, siltstone, and sandstone, are composed of
fragments of older rocks: clay, silt, and sand (38). Moreover, organic sedimentary
rocks consist of lithified remains of plants or animals, and the most common
examples are coal, which is made up of decomposed and compacted plant remains and