Earth's Layers
The outermost layer of Earth where we live.
the crust
The Earth formed approximately this many billion years ago.
4.54 billion years ago
Plates move on top of this softer layer beneath them. (A____________________)
The scientist who proposed continental drift.
Alfred Wegener
This boundary occurs when plates move away from each other.
divergent boundary
This layer is made mostly of iron and nickel and is liquid.
outer core
This supercontinent existed before breaking apart into today’s continents.
Pangaea
This causes tectonic plates to move due to heat from Earth’s interior.
convection currents
2 observations for continental drift
1. Fossil evidence
2. Continents fit like a jigsaw puzzle
This boundary occurs when plates collide.
convergent boundary
This layer is made of semi-molten rock and allows tectonic plates to move.
What is the mantle?
Humans evolved approximately this many years ago...
200,000 years ago
What plate is Australia on?
Australian Plate
Harry Hess proposed this theory
Seafloor Spreading
This boundary occurs when plates slide past each other
transform boundary
The hottest and most dense layer of Earth.
inner core
Water may have been frozen in these space rocks that hit Earth during early formation.
Asteroids
The two plates that collided to form the Himalayas (including Mt Everest)
Eurasian Plate and Indian Plate
The original supercontinent broke apart into these two smaller (but still massive) continents
Eurasia and Gondwana
This process happens when one plate goes under another. (S______________)
subduction
The rigid outer layer made up of the crust and (upper) upper mantle. (L___________________)
lithosphere
Earth is now covered in this % of water
71%
Seven
Marie Tharp discovered these in the Atlantic Ocean
ocean ridges (Mid Atlantic Ridge)
These 2 natural disasters are most common at plate boundaries.
earthquakes and volcanoes