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Lecture notes from the Live lecture

Environmental Science
Course Code
Nick Eyles

of 2
Lecture 7
Guyots: (named after an oceanographer) A flat topped dead volcano
hot spots are usually associated with hot spot islands in the middle of oceans. Someone in the
60's asked why there was islands in the middle of the oceans, which is why we know about hot
On the islands the rocks are much younger than the surrounding ocean floor.
The youngest island which is brand new (right above a hot spot)
There is a systematic aging of the rocks as you move away from the hot spots and move down
the trail.
The orientation of the hot spot trail gives the direction for the plate movement.
Bathymetric- a map that shows water depths
Phreatomagmatic means to do with water, water will go down and hit the magma and create
steam, this leads to pyroclastic eruptions.
Pyroclastic ask- ask thats thrown up in the air and falls onto the land, or blows out onto the
water. The successive flows build up laminated sediment layers.
Cinder cone- ??
Scoria are large cinder pieces of ash
Trace fossil: the track that an organism leaves.
Predation means to eat something.
Feral means wild. In the Galapagos there was feral cats.
There are igneous rock that gets extruded and intruded
Both igneous and sedimentary rocks can change. The new rock which is called metamorphic
rock is completely different from the original rock. These are the 3 groups of rocks found on
The rock cycle only operates if there is plate tectonics and plate tectonics only occurs if there is
Lithification- turns sediment into rock
compaction- squeezing water and air out of something
A rock is a naturally formed consolidation material composed of grains of one or more minerals
A mineral is a naturally occurring inorganic crystalline solid that has a definite chemical
composition, they are the building blocks of rocks.
Crystallography- the study of different shapes of crystals, and the different mineral types.
There are 4500 different types of minerals
The most important group are the silicate minerals containing silicon and oxygen and accounts
for 90% of all minerals. A few minerals dominate such as Quartz( silica=SiO2=silicon plus
oxygen), olivine, feldspars, pyroxenes, mica, clay minerals such as kaolinite, montmorillonite.
Feldspars are the largest group (field crystals) they are found in a lot of different colours. They
are semi precious and can be polished into jewellery.
Quartz is the key mineral that thickens the magma. There is very little Quartz in basalt.
Basic rocks lack silica
Acidic rocks have much higher content of Quartz (Granite, andesite)
We identify minerals by shape, colour(most noticable but least accurate), streak (colour when
mineral ground to a find powder on a streak plate like hematite (redish-brown), silicate minerals
do not streak)
Hardness: Moh's hardness scale (1-10)
Talc (very soft)=1
Diamond= 10
Environments of deposition of sedimentary rocks:
Sedimentary environments are locations where sediments accumulate.
Abyssal plain is the deep sea floor
Each environment produces a distinct type of sediment.
Each tectonic setting produces a distinct associate of the environment, and distinct rock types.
Evaporites: Rifts fill up with water and then dries out this causes rock salts