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 PROPERTIESHardnessHardness 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.