So, I've finally started my A-level Geology course! *blows party horn* However, this isn't just any A-level course. This is geology on steroids. The first time I posted, I said I was planning on doing an AS level in Geology this year. Well, I'm doing the A2 part of the A-level as well. In the same year. That's double the work. With no official teacher. Fun.
And no, I wasn't being sarcastic there – it actually is fun. I might not be saying that when summer comes round and I'm up to my neck in study cards and revision notes, but at the moment it’s certainly drawing me in. The workload is almost undetectable. I say almost since there’s a lot of new vocabulary to learn. Minerals and structural features, mainly. This absorption of terms has been made easier with the construction of my “Geolossary”. At the end of each post I’ll be plucking a new entry from the glossary and will briefly describe the term. You lucky people.
Seeing as I'm going to have a year of stress ahead, I want to talk about what happens when rocks experience stress. It’s pretty important to be acquainted with for the construction of something, so it’s pretty important to the people of the world. You've all seen photos of layered sediments all twisted and turned or snapped and shifted, but you've probably wondered what caused one rock face to fold and one to experience a fracture. Well, it’s not the processes that cause these two distinct features. It’s the rocks themselves.
Deposition of rock particles and minerals form flat beds which are eventually compacted into sedimentary rock. These beds then find themselves being compressed or stretched due to ongoing tectonic forces. After a while, these once flat beds could look very different indeed.
Rocks which are soft, hot and deep into the Earth’s crust are easier to move and bend. They behave plastically. During tension, the rock will be stretched thinner than it once was. During compression, the rocks curve into a fold.
Harder, cooler rocks nearer the surface may fold slightly, but eventually, they’re going to snap. They are too brittle to bend. Forces produce faults in brittle rocks with the rocks on either side of the fault moving in different directions depending on what force it’s experiencing.
As we all know, most earthquakes are located on faults, so it’s vital for scientists to know the brittleness and ductility of the rocks we’re living on. If there are strong tectonic forces occurring near a fault line then strong seismic activity may happen. Not only will the ductility of the rocks determine the effects of an earthquake, but it is also crucial for construction and infrastructure. The public need to get rid of the stereotype that geology is just looking at rocks and fossils. If the knowledge of the Earth were to disappear daily life would grind to a halt.
TG's Geolossary Pick #1:
MAFIC – Mafic rocks and magma are rich in magnesium and iron. The “ma” part of the word coming from “magnesium” and “fic” from “ferric” – a word used to describe iron-containing materials. These rocks are mainly found making up the crust at the bottom of the ocean, but can also be found on volcanic land, for example, the runny lava dribbling from Hawaii. The lava is less viscous and the rocks are denser than those found on continents.