Term 2 Test (Earth) Flashcards
What are the three layers of the Earth, organised by chemical composition?
Crust, Mantle, Core. The crust consists of granitic and basaltic rocks and the ocean; the mantle consists of silicate materials and the core consists of iron with nickel and sulfer.
What are the lithosphere and asthenosphere, and how are they different?
The lithosphere is the top layer of the Earth’s mantle, and the asthenosphere in the layer just below, also a part of the mantle. While the lithosphere is rigid, the asthenosphere is of a plastic consistancy.
What is the mesosphere?
The mesosphere is the lowest layer of the mantle, and is rigid.
What is the difference between the inner core and outer core?
The outer core is liquid, whilst the inner core is the very centre of the Earth and is rigid.
What are tectonic plates?
The top of the Earths’ crust is made up of giant plates, all moving extremely slowly at different speeds and directions. There are 7 main plates and many smaller ones. The movements and formations of these plates is called ‘Plate Tectonics’, and scientists use it to explain continental drift and land formations.
What are boundries (in context of plate tectonics)?
Where 2 plates meet is called a boundry, and there are 3 boundry types.
What are the 3 types of plate tectonic boundries?
Divergent boundries, Convergent boundries, Transform boundries.
What are divergent boundries?
Tectonic plates move apart from each other, causing a breakage in the lithosphere, which then sinks into the asthenosphere and becomes what is called a rift. Magma seeps in to fill gaps and hardens to form a new layer of the Earths’ crust. This is how scientists explain the expansion of the sea floor.
What are convergent boundries?
The land masses of similar density resist subduction and instead fold upwards. This creates volcanoes and mountain ranges.
What are transform boundries?
2 plates slide against each other in different directions. The movement causes energy to build up, which is then released and felt as earthquakes.
What is continental drift?
Continental drift is the theory of how th Earth bagan by having a ‘supercontinent’, which they called Pangaea, and over time, through the movement of plate tectonics, it split into the continents we have today.
What is the evidence of continental drift and plate tectonics?
Matching fossils and complimentary coastlines on opposite continents prove continental drift, and mountains and volcanos form only on plate tectonic boundries.
How does heat and convection currents affect tectonic plates movement?
Heat from the Earths’ interior causes currents of hot rising magma and cooler sinking magma to flow, moving the crust along with them. Convection currents occur in the mantle, due to the heating of the Earths’ interior.
What are sedimentary rocks?
Sedimentary rocks are rocks made from particles and sediments that have been gathered and compacted together. There are 3 types of sedimentary rocks.
What are the 3 types of sedimentary rocks?
Clastic sedimentary, chemical sedimentary and biogenic sedimentary.
Clastic sedimentary are rocks made up of broken pieces of other rocks called ‘clasts’. These rocks form in layers and are compacted and cemented.
Chemical sedimentary rocks form when minerals have dissolved or crystalised inside of sediments, or water has evaporated and left behind crystals.
Biogenic sedimentary rocks are when sediments from once living plant and animal remains build up and are cemented together.
