Earth Sciences Grade 8

Inner Core

The very middle of the Earth, solid, made of metal, very hot.

Outer Core

Surrounds the inner core, liquid metal, makes Earth’s magnetic field.

Mantle

Thick layer of rock that moves slowly, just below the crust.

Crust

Thin, hard layer on the outside where we live.

Divergent Boundary

Plates move apart, creating new land between them (like in the ocean).

Convergent Boundary

Plates crash into each other, resulting in mountains or volcanoes.

Transform Boundary

Plates slide sideways past each other, which causes earthquakes.

Continental Drift Evidence

Fossils found on distant continents, showing continents once connected.

Evidence for Plate Tectonics

Ocean floor patterns and earthquakes at plate edges show crust movement.

Cinder Cone Volcano

Small, steep volcano made from ash and rocks.

Strato Volcano

Tall, cone-shaped volcano that can explode.

Shield Volcano

Wide and flat volcano with gentle eruptions of thin lava.

Lava Dome

Volcano where thick, sticky lava piles up near the top.

Igneous Rock

Formed when hot melted rock (magma/lava) cools.

Sedimentary Rock

Made when bits of rock get pressed together.

Metamorphic Rock

Rocks that have been changed by heat or pressure inside the Earth.

Crystals Formation - Slow Cooling

Results in big crystals.

Crystals Formation - Fast Cooling

Results in tiny crystals.

Physical Weathering

Rocks break apart from heat, cold, or freezing water.

Chemical Weathering

Rocks are altered by chemicals, such as acid rain.

Biological Weathering

Plants or animals break rocks, like plant roots growing.

Igneous Rock Identification

Look glassy or have crystals, not layered.

Sedimentary Rock Identification

Have layers, may contain fossils.

Metamorphic Rock Identification

Wavy or banded patterns, sometimes shiny.

Moh’s Hardness Scale

A scale to measure mineral hardness from 1 (softest, talc) to 10 (hardest, diamond).