History of Planet Earth

History of Planet Earth

Describe how the formation of and changes to rocks record the story of Earth's history

In this case the ammonites are the youngest fossils since they are at the top.

The oldes fossils are the trilobites because they are at the bottom​

Remember- oldest rock layers are at the bottom

SUPERPOSITION

Rock layers at the bottom are the oldest!

Igneous rocks- come from volcanic activity

Ex: Obsidian

Metamorphic Rock- made by heat and pressure

Ex: Slate

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Sedimentary Rock- come from accumulatiom or deposition of mineral or organic particles

Ex. Sandstone and limestone

Multiple Choice

An area is rich in igneous rocks of the type that forms on Earth's surface. Which statement can be made about this area?

• It is likely to have experienced volcanic activity in the past.

• It is likely to be rich in animal and plant fossils.

• It is likely to be the remains of an old mountain range that has since eroded.

• It is likely to have once been a river basin.

Multiple Choice

A geologist finds an area with a lot of slate, a type of metamorphic rock, on the surface of the land. What might this indicate about Earth’s history in this area?

• The land in this area was once on a tectonic plate boundary.

• The land in this area was once under a shallow sea.

• The land in this area has recently sunk and then risen again due to the instability of Earth underneath it.

• The land in this area was once underground and subjected to heat and pressure.

Multiple Choice

A geologist finds a hillside that has been cut away to reveal four level layers of rocks, one on top of another. Which conclusion can the geologist draw about the history of this area?

• The rock layers built up over time, with newer layers forming on top of existing ones.

• The rock layers built up over time, with newer layers forming beneath existing ones.

• Two of the rock layers formed as a result of volcanic activity.

• All four rock layers were deposited at once during a landslide.

Multiple Choice

A scientist is studying a rock formation. She determines that one of the layers in the formation is volcanic ash. She then finds some animal fossils a few layers below the volcanic ash. Which conclusion can the scientist draw?

• The animals lived before the volcano eruption.

• The animals lived at the same time as the volcano eruption.

• The animals lived after the volcano eruption.

• The animals may have lived before, after, or at the same time as the volcano eruption. More information is needed.

Describe how fossils form and identify how fossils record the story of life's history on Earth

Fossils are...

• Remains of an extinct organism found in a rock layer

• can be plants or animals

• evidence of an organism's lenght, height, types of eaten food

• RARE!

• Bone fossils form when minerals replace the deterioratin bone

• Trace fossils are footprints, trails, burrows or other traces of an animal rather than the animal itself

​AMBER is another type of fossilization where the organism is entrapped and preserved. Amber comes from the resin of a tree

Superposition

-Rock lauers at the bottom are the oldest

• So fossils at the bottom are also the oldest

• Fossils in same rock level must have coexixted at the same time

• Shows how life forms change over time

Multiple Choice

Which statement describes one way in which a fossil can preserve an organism mostly intact?

• A giant salamander’s bones are replaced by minerals over time.

• A fish dies, and rock builds up around its skeleton.

• A giant sloth leaves a footprint impression in the sand.

• A mosquito gets caught in amber dripping from a tree trunk.

Multiple Choice

A geologist finds two layers of rock in an area of grassland. In the lower layer, the only fossils are of marine organisms. In the upper layer, there are bones of terrestrial frogs and snakes. Which conclusion can the geologist draw about the history of living things in this area?

• The area was once land, and then later it was covered by sea.

• The area was once sea, and then later it was covered by land.

• The area was never terrestrial.

• The area has never been covered by sea.

Multiple Choice

Which statement describes the formation of a trace fossil?

• A saber-toothed cat gets caught in a mud pit.

• An insect gets caught in sap dripping from a tree.

• A dinosaur leaves a footprint in mud, which hardens around the impression.

• A marine organism dies, and its shell is replaced by minerals over time.

Multiple Choice

Many layers of the Grand Canyon in Arizona contain marine fossils. What does this suggest about Earth’s history in the area?

• The area was under the ocean at different times in the past.

• All of Earth was underwater until recently.

• All of Arizona was recently under the ocean.

• The Grand Canyon was carved from rock by marine waters.

Multiple Choice

Paleontologists construct a model of a dinosaur from its fossilized bones and teeth. These fossils can help the paleontologists infer all of the following about the dinosaur EXCEPT...

• its length.

• its skin color.

• its height.

• the type of food it ate.

Identify how layers of rock and fossils can be used to determine relative dates of events in Earth's history.

From the fossil record above, scientists can determine the area was first a FOREST because of the fern and leaf imprints. As time passed, it became a LAKE based on the freshwater clam shells and fish bones.

Key beds

Are rock layers that are spread over a very large geographical area and are distinctive in some way.

Because key beds cover a much larger area than most rock layers, they are useful for determing RELATIVE rock ages of rocks in different locations.

Ex: A think rock layer that is unusually rick in rare elements and is found in almost all places on Earth

Relative age is the age of a rock layer (or the fossils it contains) compared to other layers. It can be determined by looking at the position of rock layers.

Absolute age is the numeric age of a layer of rocks or fossils. Absolute age can be determined by using radiometric dating NOT by looking at rock layers.

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Relative Age VS Absolute Age of a Fossil

Multiple Choice

Scientists found trilobite and brachiopod index fossils in cliffs a great distance apart from each other. What can scientists infer about the rocks in which these fossils were found?

• the weathering of the rock

• the density of the rock

• the slope of the rock

• the age of the rock

Multiple Choice

A geologist discovers a plant imprint in a rock layer about 50 feet below the ground. During a future dig at the same site, he discovers a shell of a marine organism 200 feet below the ground in a different rock layer. What can the geologist conclude about the relative ages of the fossils?

• Both fossils are about the same age.

• The plant fossil is older than the marine animal fossil.

• The marine animal fossil is older than the plant fossil.

• Both fossils were deposited within the last 100 years.

Describe how tectonic processes generate new seafloor and destroy old seafloor

Seafloor spreading or Seafloor spread is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge

Look for videos on YouTube that model this process!!

In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass.

When a supercontinent breaks apart ocean basins form between the new continents

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Supercontinents

​When continental plates collide and are pushed forward they form mountains; Uplift

Mountain Formation

• plates separate and open up

Ocean Formation

Multiple Choice

How did the Sierra Nevada mountain range form?

• The North American Plate separated from the Pacific Plate, and the Sierra Nevada formed at the plate boundary.

• The North American Plate broke into two smaller plates, one of which sank, and the Sierra Nevada formed at the site of the breakup.

• The North American Plate started as separate plates, which pushed against each other and formed the Sierra Nevada where they joined.

• The North American Plate met with an ancient oceanic plate, causing uplift that formed the Sierra Nevada.

Multiple Choice

What happens to old seafloor when it is destroyed?

• It cools and forms mountains.

• It is mostly dissolved in water and circulated with ocean currents.

• It is melted in the mantle.

• It is immediately recirculated to rifts to make new seafloor.

Multiple Choice

When new seafloor is being added at a rift, in which direction do the plates on either side of the rift move?

• Both plates move toward the rift.

• One plate moves up, and the other plate moves down.

• Both plates move away from the rift.

• Both plates move parallel to the rift, in opposite directions.

Multiple Choice

Which phrase best describes the oceanic crust in an area where seafloor spreading is taking place?

• Fractured and thin enough for new seafloor to push through.

• Broken up into a series of large undersea volcanoes.

• Very solid for at least five kilometers beneath the seafloor.

• Mostly liquid for about one mile on either side of the rift.