Its All Relative...
Dating rocks and events based upon other rocks and events
What is...
Relative dating?
Define a dike and a sill
What type of rock do they form from?
What is...
Magma squeezed into vertical cracks that cut across rocks and harden
Forms from igneous rock
Paleontologists are
What is...
Scientists who study the history of life on Earth through fossil evidence
The process used to determine a more precise age of fossils and the earth
What is...
Absolute dating?
A sample of wood found in an ancient tomb contains 25% of its original carbon-14. The age of this wood sample is approximately:
What is...
11, 400 years old? (5,700 X 2 half lives)
Rock layers in different places can be matched up by matching up rocks and fossils in the layers
What is...
Correlation?
An unconformity is (regular)
What is...
An erosion of the rock layers followed by new deposition
Some rock records are not complete, these have gaps that are called unconformities
Unconformities develop where rock layers are removed by erosion or plate tectonics
Unconformities can also develop when time passes without any further rock being laid down
Define a fossil and the conditions necessary for their formation.
What are...
preserved remains, imprints, and traces of once-living organisms.
Fossil formation requires that the organism is protected from scavengers and bacteria and that it is quickly covered by sediments to prevent decay.
Process that occurs when the number of protons/neutrons in an atom is changed and a new element is formed.
What is...
Radioactive decay?
A radioactive isotope under goes a half life every 22 years. How much of the original isotope would remain in a 20 gram sample after 88 years?
What is...
1.25 grams? (4 half lives, 1-10, 2-5, 3-2.5, 4-1.25)
Three main types of rocks and how they form
What is...
Sedimentary - pressure and compaction of sediments, dead plants and animals
Igneous - formed from other melted rock
Metamorphic - formed from other rocks changed by heat and pressure
3 Types of Unconformities and explain them
What are...
Angular Unconformity: original rock layer becomes tilted
Disconformity: the original rock layer is present, then a layer becomes eroded away and new deposition occurs. Even though layers are still horizontal there is still a gap in the rock history
Nonconformity: occur where intrusive igneous rocks or metamorphic rocks, are overlain by sedimentary rocks formed at the Earth’s surface. The nonconformity can only occur if all the rocks overlying the metamorphic or intrusive igneous rocks have been removed by erosion.
Index fossils are and find the index fossil(s) in each layer in Google Doc
See Google Doc
What are...
Fossils that can be used to date the rock layer in which it is found.
Good index fossils are ones where organisms would have been around for a limited time.
Good index fossils are ones where organisms would have to have been found world-wide.
Layer A: both fossils
Layer B: both fossils
Layer C: diamond and cone shaped fossils
Layer D: cone shaped fossil
The stable daughter particles found in rocks and fossils come from
What is...
Radioactive parent particles?
A sample of carbon-14 under goes 3 half lives. What percentage of the sample has turned into Nitrogen-14?
Wha is...
87.5%? (1-50:50, 2-25:75, 3-12.5:87.5)
Look at the relative dating picture on the Google Doc and list the rock layers in order from oldest to youngest (including the events)
See Google Doc
What is...
C, F, G, J, D, K, I, H, A, E, fault, disconformity, B
Look at the 3 types of unconformities on the Google Doc and correctly label each one
See Google Doc
What is...
Left to Right
Angular, Disconformity, Nonconformity
Type of fossil and how it is formed
See Google Doc
What is...
A cast and mold
A mold forms when hard parts of an organism are buried in sediment, such as sand, silt, or clay.
The hard parts completely dissolve over time, leaving behind a hollow area with the organism’s shape.
A cast forms as the result of a mold. They are opposites. Water with dissolved minerals and sediment fills the mold’s empty spaces. Minerals and sediment that are left in the mold make a cast.
Oxygen and Carbon are two elements that have several different forms consisting of different numbers or protons and neutrons called
What are...
Isotopes?
The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?
What is...
12.5 g remaining?
7.2 / 2.4 = 3 half-lives
(1/2)3 = 0.125 (the amount remaining after 3 half-lives)
100.0 g x 0.125 = 12.5 g remaining
The 5 Laws of Relative Dating and what they explain
What is...
Law of Original Horizontality (all rocks laid down flat initially)
Law of Superposition (older rocks below younger rocks)
Law of Lateral Continuity (sedimentary layers extend sideways in all directions until they reach a barrier)
Law of Inclusions (if one rock layer contains fragments of another rock layer, that layer must be younger than the fragments of rocks it contains)
Law of Cross-Cutting Relationships (any geological feature that cuts across, or disrupts another feature must be younger than the feature that is disrupted)
Look at the relative dating picture and list the rock layers in order from oldest to youngest (including the events)
See Google Doc
What are...
A, B, D, E, F, C, fault line/earthquake, G
A, B, D, E, F, fault line/earthquake, C, G
*As long as you can justify your answer with the laws
The type of fossil represented in the picture and the three substances they can be preserved in
See Google Doc
What is...
Original remains in amber, ice, and tar
Some processes preserve the remains of organisms with little or no change. Some remains are preserved when organisms become trapped in tar. Ancient organisms also have been preserved in amber. Amber is the hardened resin, or sap, of evergreen trees. Freezing is another way in which remains can be preserved.
The time it takes for half the atoms in a sample to change from a radioactive isotope to a new stable atom
What is...
A half-life?
After 24.0 days, 2.00 milligrams of an original 128.0 milligram sample remain. What is the half-life of the sample?
What is...
4 days?
128 mg --> 64 mg --> 32 mg --> 16 mg --> 8 mg --> 4 mg --> 2 mg.
24 days / 6 = 4 days