Geol 5, Lab #12: Fossil Indicators of Age, Environment, and Correlation (Access is reserved to SMC students only)

Fossils and Age Determinations
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question 1, page 161
from bottom to top: C, O, S, D, M
or Cambrian, Ordovician, Silurian, Devonian, Mississippian

question 2, page 161
You shoudl draw the respective ranges for fossils F-1 and F-2. Ranges go from the bottom of the oldest Period to the Top of the youngest Period, and are indicated by a straight line closed, top and bottom, by a horizontal mark.

F-1 (trilobite): C, O, S
F-2 (crinoid): S, D, M

The two fossils only overlap during time S (Silurian)

question 3, page 161
Region IV only contains F-1
F-1 is found alone (without F-2) only during the Cambrian and the Ordovician

The rocks in unexplored region IV were deposited during the Cambrian and the Ordovician Periods

question 4, page 161
Region V contains both F-1 and F-2
These two fossils ranges overlap only during the Silurian

The rocks in unexplored region V were deposited during the Silurian Period

question 5, page 162
The only time when Fossil F-1 is found by itself is during times C and O (Cambrian and Ordovician)

question 6, page 162
The only time when Fossils F-1 and F-2 are found together is during time S (Silurian)

question 7, pages 162 and 163
skipped

Biozones and Biostratigraphy
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question 1, page 164
skipped

question 2, page 165
skipped

A Graphic Method of Correlation
Interpretation of an Outcrop in Southern Illinois
Interpretation of an Outcrop in Central Illinois
Fossils and Paleoenvironments
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question 1, page 169
Benthonic and planktonic foraminifera

question 2, page 169
Organisms with soft parts only, no shells or hard, mineralized parts or structures

question 3, page 170
Shells of foraminifera can be retrieved intact from cuttings, the rock fragments obtained during drilling operations. If one knows at what depth certain benthic foraminifera live, one can estimate the ancient depth of the ocean bottom. If several wells are drilled, it is possible to observe trend or directions towards ancient shallow-waters areas and shorelines.

The Habitat of Marine Life
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question 1, page 172 (left column)
A bathymetric change refers to a change in the depth of the water column. The question is asking if, based on the kind of fossil you find, you can indicate how the depth of that ancient ocean changed.Since calcareous sponges and algae live in shallow waters (on the shelf) and siliceous sponges and cephalopods instead live in deeper waters, you can safely say that the sea level has been rising (that is the answer to the question)

question 2, page 172 (left column)
Because cephalopods and planktonic foraminifera live in the water column and not at the bottom of the ocean, so they are not tied to a specific depth of the ocean bottom

question 3, page 172 (left column)
The layer was deposited in shallow waters, on the shelf

question 4, page 172 (left column)
from page 170: "The forms of life found in the neritic-benthic zone require at least some light. That biologic requirement is readily met over most of this shallow zone where sunlight penetrates all the way to the ocean floor"

question 5, page 172 (left column)
Because during low tides the ocean bottom might become exposed and sea creatures can remain in the water saturated zone by digging deeper and deeper

question 1, page 172 (right column)

The four definitions are listed in the book in the same order, from top to bottom, in which they should be inserted in Figure 12.11, page 172

question 2, page 172 (right column)

There are three unconformities (all three are disconformities). Draw the arrows
Mostly, there is a sharp change in fossil (and lithology, but that is not as important), rather than a gradual one

question 3, pages 172 and 173 (right column)

Paleozoic (for corals, figure 10.27, page 117; bryozoans, 10.29, page 119; brachiopods, 10.31, page 121; ferns and scale-tree fossils, 11.43, page 157)
Cenozoic (woolly mammoth only existed during the Quaternary, which is part of the Cenozoic)
Mesozoic (for angiosperms, like oak, figure 11.41, page 155)

Invertebrate Trace Fossils
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