Dating of rocks fossils and geologic events lab answers | Journal des Appels d’offres
Laboratory Eight Dating Of Rocks Fossils And Geologic Events Answers Answers to Lab 8, part 1 questions, Last Updated • February 3, Activity . Activity Sequence of Geological events in a cross section. Using Index Fossils to Date Rocks and Geological Events The geological time column Examine the photos in the lab manual on p and answer the following questions. Is dating. Lab comprise units of fish and answer the first lab comprise units of Chapter 8 dating a rock but what geological events that a fossil or geologic time.
What kind of contact separates the unit in the lower right from the gravels? Is it a conformable contact? Why or why not? What is the geologic history of the rocks and sediments shown here? The fellow in the lower right with the red shirt on is Rich Keziran, a well-known history teacher at MPC. What do you think he is thinking as he gazes up at these rocks? The Grand Canyon Notice the two series of sedimentary rocks: The Paleozoic series is flat-lying and lies above the Grand Canyon series.
Draw a sketch or cartoon that shows the difference in dip between the two groups of sedimentary rocks. What is the type of contact between the two groups of sedimentary rocks? What must have happened during the time period represented by this contact? In other words, what happened to create this contact? What is the geologic story or sequence of events that can be inferred by looking at the rocks that comprise the Grand Canyon, as seen in this image?
Plutons in Chile The larger diagram shows a mountain-sized view of the contact, whereas the inset shows a closeup view of the contact. What evidence is seen on the close-up the inset to support your answer? Which is older, the dark rock or the light rock?
- Lab 8: Relative and Absolute Geological Dating Lab
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- Dating of rocks fossils and geologic events lab answers
How can you tell? Garrapata Beach a What is the origin of the sedimentary rocks in the lower half of the outcrop? Which is older, the granite or the sedimentary rock? Which is older, the slightly weathered granite or the fresh granite?
How do you know? Geologic maps and illustration use standard symbols to represent specific rock types. Understanding these lithologic or rock symbols is essential to interpreting geologic maps and graphics. It will also help you complete the next part of lab. Copy the symbols from the front of class onto your lab worksheet. Place the letter of the oldest unit on the bottom of the list and letter of the youngest unit on the top and fill in the rest appropriately.
You may choose to do either cartoon B or C: You may choose to do B or C: You do not have to do both Cartoon C. What kind of unconformity separates unit B from unit P? What kind of unconformity separates unit E from the underlying units? N refers to the time the house was built. Fault T cuts Formation A. Disconformity — erosion or non-deposition generally lasting years to millions of years. Angular unconformity requires deformation and erosion, generally millions of years or more.
Nonconformity marks erosion clear down to crystalline basement rocks below the sedimentary basin.
Often this is the basal unconformity for an entire sedimentary basin. The rocks below are deformed igneous and metamorphic that are hundreds of millions to billions of years older than the overlying sedimentary succession.
Work through examples 8. Cross sections represent the layered view of the Earth and its rocks as seen at a roadcut, along a stream valley or in a sequence of boreholes in the subsurface. There are 4 cross sections,3 hypothetical ones but one real one from the Inner Gorge of the Grand Canyon.
Note the legend blocks below so you can tell igneous intrusions which baked the rocks they cut from eroded plutons covered by gravel of their own detritus.
Generally sediments are deposited in horizontal layers. If they are dipping tilted there has been enough time after their deposition and lithification to uplift and erode them in a mountain building episode.
In geological sequences, unconformities for erosion or non deposition actually represent more missing time than is represented by the deposition of a single layer or sequence. Therefore, we include unconformities in the sequence as they represent the biggest blocks of time. Often an unconformity is more than one type depending on what the underlying layer is like.
Dating of rocks fossils and geologic events lab answers - video dailymotion
For example a flat lying strata that overlies both dipping beds and crystalline rocks is both an angular unconformity and a non-conformity. The present day erosional surface nonconformity on the Canadian Shield is missing on average 2. The Tertiary Period is further subdivided into: Paleocene, Eocene, Oligocene, Miocene and Pliocene.
Fossils are unique impressions or mineral replacements of once living biota. The average lifetime of a species, be it a microscopic species of plankton or a massive mammal, is about 2 Ma. Thus recognizing and telling one fossil species from another gives a pretty well defined interval of time. Groups of closely related animals live longer than individual species. For example there have been horse-shoe crabs since the Lower Paleozoic, but there have been hundreds if not thousands of different species.
Marine strata preserve the best fossil records. Paleontologists use the overlapping and sequential range zones of different groups of fossils. Identifying species with easily distinguished shapes is the key to interpreting relative ages.
Lab 8: Relative and Absolute Geological Dating Lab
Now that we have used volcanic ash beds or lavas intercalated with sediments to assign absolute radiomentric ages, we know the Cambrian began million years ago. Finally, using the absolute age scale along the left edge of the diagram, assign an absolute age to the fossil assemblage pictured.
Here we are using long lived groups and our precision is less but the general idea is the same. For example, if a stratum contained Shark teeth and the brachiopod Chonetes, we can say it was sometime between Late Devonian and Latest Permian for relative age and between Ma and Ma from the overlap of the 2 range zones for its absolute radiometric age.
Examine the photos in the lab manual on p and answer the following questions: Analyse the fossils on p in the top frame and these of the same types. All of these fossils are typically found in fine grained micrites microcrystalline limestone mud.Laws of Relative Rock Dating
To what 2 groups of marine invertebrates do they belong? What is the absolute age range, from the oldest possible age to the youngest possible age when both of these index fossils coexisted? Analyse the fossils on p in the middle frame and these images above of the same types.
Unlike what the book says these are never found in Ohio outside of museums! These fossils are typically found in both limestones and detrital sandstones across much of the world including parts of Canada from Vancouver Island to Saskatchewan.
At the very least, what system is missing from cross section 8.
Lab 8--Relative Dating
With fossils, we do not know from just one occurrence whether we have the very earliest occurrence of a fossil or the very latest, or somewhere in between. This introduces some error or uncertainty in figuring the interval of missing time.
Assuming the lower trilobite was the very first of its kind and the upper trilobite was the very last of its kind, what is the maximum amount of time missing: