Geological history of the earth Fossils Rock and Fossil Formation Dating the Past Geological Time Geological history of the earth

Where are fossils formed? What can become a fossil? Formed in ________________ ___________________________ Can be bone, _____, pollen grain, ________, or ________________

What are the types of fossils? ______________________- minerals turn the bone or shell to stone. Mold- ____________________ left by soft tissue dissolving away. Cast: A mold filled in with _________________. ____________________: The impression, like a __________________, left in soft sediment that hardens into rock over time.

Petrification Minerals turn the ________________________.

Molds _______________________________ dissolving away.

Casts A mold filled in with ______________________.

Trace fossils/imprints The impression, ___________________, left in soft sediment that hardens into rock over time

How do entire organisms get preserved? __________- A mastodon was found in Canada

How do entire organisms get preserved? Amber- _______________________________, which hardens into the mineral Amber.

How do entire organisms get preserved? _____________________- Capture animals that come to feed on other captured animals

How do we interpret fossils? Law of Superposition- __________________ are usually ____________________________. (Like the clothes on the floor of your room).

How do we interpret fossils? ______ fossils- come from _________________ or periods. Used to piece together the geological record.

How do we interpret fossils? Unconformity- a _____________________ sequence indicating interruption of sedimentation, commonly accompanied by ___________________ below the break.

How do we interpret fossils? Faults- ___________ than the rock layers that contain them.

How do interpret fossils? _________________- magma forces its way into layers of rock. Intrusions are _________________ than the rocks they intrude into.

How do we interpret fossils? __________________- If magma reaches the surface of the earth, it forms an “extrusion”, a pool which hardens into igneous rock. The extrusion is _________ than the rock it overlays.

How do we date the past? The _____________________, some containing fossils, determine which were deposited first.

What are the theories for dating rocks? First theory- sediment is deposited at _________ ______can determine the age of any unmetamorphised sedimentary rock layer and fossils it contains. Problem- sediment is NOT deposited at a steady rate…

How do we date rocks? ____________________________: 1. Atom of radioactive elements decays at a __________________________ 2. Atoms form different, more stable elements, called _____________________. 3. the time it takes for a radioactive element to decay to half of the original amount is its __________________.

How do we date rocks? 4. Half-life of elements can be fractions of a second to _______________________. 5. Since we know the half-life’s of most elements, we can date many rocks by _________________________.

What is carbon dating? _________ isotope Carbon-14 is used to date relatively __________________ Works well for dating ancient _______________ remains Page 603 has list of elements and their half-lives

What is varve? Varve- sediment layers laid down each year or season in __________________

How old are the oldest rocks on earth? The oldest rocks found on the Earth are in__________ __________ and are over 4 billion years old Moon rocks are even older, and scientists accept that the Earth is the same age as the Moon because they formed at the __________.

What are the eras of geological time? Precambrian Era- ______ form, ____________ increases in the ______________. Life is simple; bacteria, algae, jellyfish, clams, coral –___________________ The landmasses are low and flat and large, a with low ____________ quite abundant.

What are the eras of geological time? ___________________________ seas increase in size, encroach on land ________________ thrive; ________, sponges, snails, worms, and other ___________ critters.

What are the eras of geological time? Ordovician- life in seas; ___________________, invertebrates advance; lots of ______________ critters On land, mountains and ____________________ continue

What are the eras of geological time? Silurian- first __________________, air breathing arachnids, and __________________ Shallow seas dominate, _____________ climate and topography are abundant. _______________ occurring

What are the eras of geological time? Devonian- swampy forests grow; _______________ arrive, as do sharks and insects ___________________ appear Uplift and erosion continue. Still quite _____________ and ________________.

What are the eras of geological time? Carboniferous- swamps abound in the lowlands. First ____________, reptiles, and flying insects. Seed-bearing _____________ grow. Mountain building going on. ______________ much of the planet, swamps still in lowland areas. ___________.

What are the eras of geological time? Permian- first ______ bearing plants. Ferns, fish, amphibians, and _____________ thrive. Big die-out of sea life ___________ building continues. Climate dries out, forests thrive.

What are the eras of geological time? Triassic- first ____________________________, modern coral, fish, and ____________ develop. ____________ still thrive, but plains to emerge.

What are the eras of geological time? Jurassic- fist _______, trees thrive, mammals continue to develop __________________ grow, volcanoes are active

What are the eras of geological time? Cretaceous- first _________ plants, first placental mammals develop. Dinos die out, and so do many sea living _______________. Volcanic time. ___________ layer found in rocks of this period. Often comes from ___________, seldom found anywhere else.

What are the eras of geological time? Tertiary- first ___________, primates, humanoids develop. Mammals look modern. Tropical climate; lots of ___________________.

What are the eras of geological time? Quaternary- first _______ beings appear, Wooly Mammoth die out, human culture develops. ________________ dominate. We are still in an ice age that is __________________.

How does life change on earth? _________________- change over time Occurs due to environmental ___________________ Supported by the _________________ record.