SCIENCE 10 - TECTONIC PLATES

tectonic plates

a large, rigid section of the Earth's lithosphere that moves and interacts with other plates on the Earth's surface.

GNSS/GNP

provides direct, present-day evidence of plate movement by repeatedly measuring

changes in the precise position of a ground station.

• determines the direction, displacement, and average rate of movement.

outward on both sides

The pattern of seafloor rock ages shows that new oceanic crust forms at a mid-ocean ridge and gradually moves ___________.

nearest

The youngest rocks are found ______ the mid-ocean ridge.

increases

Rocks become progressively older as their distance from the ridge ________.

downward, beneath

The locations and depths of earthquakes form a recognizable underground pattern that allows scientists to infer that part of Earth’s crust is moving _____ ______ another section.

organized

Earthquakes are not always randomly distributed; they can form an _____ pattern.

InSAR

Compares radar signals from satellite images taken over the same area at different

times.

• Maps ground movement toward or away from the satellite across a wide area.

VLBI

Radio telescopes observe the same distant quasar and compare signal-arrival times.

• Measures changes in the distance and direction between telescopes.

Satellite Laser Ranging

Sends a laser pulse to a satellite reflector and times the returning light.

• Calculates the precise distance between the station and the satellite.

Seismic Monitoring

Seismometers record P waves, S waves, and surface waves from earthquakes.

• Locates earthquakes and describes their magnitude, depth, and fault motion.

geological evidence

Scientists study displaced landforms, fault layers, rock ages, and magnetic patterns.

• Records past fault movement and long-term seafloor spreading.

earth

is a dynamic planet, constantly changing due to both internal and external forces.

compositional

this layer of the earth refers to what it is made of

mechanical

this layer refers to how the Earth behaves

crust

Outermost, thinnest layer (5–70 km thick)

continental crust

type of crust which is thick, less dense, made of granite

oceanic crust

type of crust which is thin, dense, made of basalt

silicon, oxygen, aluminum

-composed mostly of _____, _____, _____

-makes up less than 1% of Earth’s mass

mantle

-extends from the base of the crust to 2,900 km deep

-largest layer by volume (84%)

-composed of silicate rocks rich in magnesium (Mg) and iron (Fe)

-solid, but flows slowly

outer core

-liquid, and its motion creates Earth's magnetic field

-composed mainly of liquid iron and nickel

inner core

-solid, due to the immense pressure despite extreme heat

-made mostly of solid iron and nickel

plate boundaries

The regions where two or more tectonic plates meet and interact are called

divergent

-occurs when two plates move away from each other.

convergent

-the two plates push into each other

transform

-occurs when two plates slide past each other horizontally

-plates move alongside each other, in the opposite direction or in the same direction at different speeds