Week 9 - Earths Internal Heat (Unit 2) Flashcards
What is the geosphere?
The part of the Earth that includes the surface of the planet, interior of Earth, all rocks, ores and minerals, and the processes that shape the Earth’s surface.
What is the significance of Earth’s systems operating together?
Any event affecting one Earth system will have a knock-on impact on all the others, which affects resource availability.
How long ago is it believed that Earth formed?
Approximately 4.5 billion years ago.
What are planetesimals?
Small early planets formed from the gathering of gas and dust due to gravity.
When is the first fossil evidence dated to?
540 million years ago.
What epoch are we currently in?
The Holocene epoch.
What is the crust of the Earth?
The outer shell of the Earth that formed as the planet cooled down.
What are tectonic plates?
Plates composed of the crust and parts of the upper mantle that float on the mantle.
What is the temperature of the Earth’s inner core?
Up to 5500 °C.
What is the outer core composed of?
Liquid iron and nickel.
What causes frictional heating in the Earth?
Denser materials sinking to the centre of the planet.
How deep is the mantle?
2885 km deep.
What generates heat in the Earth’s internal structure?
Decay of radioactive elements.
What are the sources of Earth’s internal heat? List them.
- Extra-terrestrial impacts
- Gravitational contraction
- Decay of radioactive elements
What was observed in the early 20th century regarding continents?
Similar fossils and rocks existed on continents that are now thousands of miles apart.
What is the theory of plate tectonics?
The theory that continents were once part of a supercontinent (Pangaea) that broke up and continues to move.
What drives plate tectonics?
A convective process with heat transferred from the Earth’s core into the mantle.
What are mantle plumes?
Hot masses that rise in the mantle, sometimes causing surges of heat.
What are the two types of crust that make up tectonic plates?
- Continental crust
- Oceanic crust
How thick can continental crust be?
Ranging from 30 to 70 km thick.
What is oceanic crust made of?
Dense basaltic rock.
True or False: Oceanic crust is thicker than continental crust.
False.
Fill in the blank: The crust can be up to _______ thick in mountain belts.
70 km
