PROCESSES OF ROCK AND FOSSIL FORMATION

Comparisons of rocks and minerals and how they are related

MINERAL DEFINITION

A mineral is a substance found in nature. They are solid, non-living substances.

Minerals are made of atoms Earth has more than 3,500 different

kinds of minerals.

MINERAL PROPERTIES

Crystal shape – A mineral’s atoms can make shapes called crystals. The crystal gets its shape from the way the atoms inside are arranged. Crystals have smooth, flat surfaces and sharp edges.

Cubic orthorhombic rhomboid

MORE MINERAL PROPERTIES

HardnessHardness test – Mohs scale from 1 – 10Talc #1 --------- Diamond #10

Streak – The colored line a mineral makes on a plate.

MORE MINERAL PROPERTIES

Some minerals break apart in a special way.

Cleavage Fracture

Color Luster

ROCK DEFINITION

When minerals mix together, they become rocks.

Magma is made from many minerals. As magma cools, the minerals harden

together and become rocks.

IGNEOUS ROCKS

Igneous rocks are rock made from cooled magma.

Obsidian Granite Basalt

METAMORPHIC ROCKS

Metamorphic rocks are changed by being heated and squeezed.

Metamorphic rocks are usually very dense.

Gneiss Schist Marble

SEDIMENTARY ROCKS

Sedimentary rocks are made of pieces of sediment that have been glued together.

The glue for the rocks is made when water dissolves some minerals which later harden.

Breccia Conglomerate Sandstone

ROCKS UNDERGO CHANGES OVER TIME

The rock cycle is continuous and moving in all possible directions.

ENERGY IS RESPONSIBLE FOR CHANGES TO ROCKS OVER TIME.

It takes mechanical energy to move the sediments to form sedimentary rocks.

Magma has a tremendous amount of heat to melt minerals together.

It requires tremendous heat and pressure to form metamorphic rocks.

EROSION

Erosion changes the surface of the Earth by wearing away the materials.

mudslide water erosion Dust storm

WEATHERING

Weathering changes Earth materials.

Chemical Mechanical

SOIL FORMATION

Soil forms when rock has been weathered and eroded.

FOSSILS

Fossils are the remains or traces of ancient life.

They are at least 10,000 years old. They can be mineralized samples such

as petrified wood. They can be materials from the organism

like bones and fur. They can also be traces of the organism

like footprints or nests.

FOSSIL FORMATION

Fossils are most commonly formed when:

1. An animal dies and its skeleton settles to the seafloor where it is buried by sediment.

2. The sediment thickens and begins to turn to stone.

3. The skeleton dissolves and a mold is formed. 4. Minerals crystallize inside the mold and a cast is

formed. 5. The fossil is exposed on Earth’s surface due to

erosion.

DEPOSITION

Deposition happens when the energy causing the transportation of sediments is unable to move them further.

Therefore, they are deposited in an area.

Sediments are deposited in layers.

RELATIVE AGE

Rocks are dated by relative age. The older rocks are said to be at the

bottom, while the younger rocks are normally on the top.

FOLDING

These rocks have been folded

In this case the youngest ones may not always be on top.

FAULTING

These rocks have been faulted

Again some of the rocks have shifted, so relative age is harder to determine.

FOSSILS AS EVIDENCE

Fossils show evidence of the changing surface of the Earth.

This fish fossil found in a mountain side is evidence that there was once a water habitat in this area.

FOSSIL LAYERS Recently deposited fossil layers are more

likely to contain fossils resembling existing species than the older rock layers.

The fossils in unit O will be closer to the existing species than those in the lower units. M will contain the oldest species.

EARTH’S ENERGY CAN BE TRANSFERRED

Energy from Earth’s interior causes changes to Earth’s surface.Earthquakes Volcanoes

EARTH’S INTERIOR ENERGY

The Earth’s rock layer is broken into pieces that are in constant slow motion. From time to time, the pieces lock together, and energy that accumulates between the

pieces may be suddenly released. It travels through the Earth in the form of waves.

People on the Earth experience an earthquake.

EARTHQUAKES

An earthquake is the result of a sudden release of energy in the Earth’s crust that creates seismic waves.

These seismic waves transfer mechanical energy.

EARTH’S INTERIOR ENERGY

A volcano is an opening in the Earth’s crust which allows hot magma to escape from below the surface.

VOLCANOES

A volcano is a release of energy that built below the surface of the Earth due to heat and pressure.

Flowing magma transfers heat and mechanical energy.

EARTH’S CHANGING SURFACE

Small changes over time add up to major changes on Earth’s surface.