ANSWERS TO QUESTIONS ON PAGE 30 Answers:
1. The answer is choice “c” or Nicolaus Steno (1638-1686), one of the early founders of modern geology and stratigraphy.
Professor Abraham G. Werner (1750-1817) was a popular and influential geologist and competent mineralogist. Werner was also the leader of the concept of “Neptunism”, postulating an aqueous origin for all rocks.
William “Strata” Smith (1769-1839) was an English geologist, engineer and surveyor who developed the first nationwide geologic map of England and Wales. Smith advanced stratigraphic correlation techniques by using similar fossil assem- blages in matching rocks of the same age but of different lithologic composition. His work ultimately led to our understand- ing of the principle of biologic succession. On a personal note, I had the good fortune to see the original map by William “Strata” Smith at the Burlington House in London, headquarters to “The Geological Society” of London.
2. The answer is choice “a” or “Shells are larger and more abundant during warmer climate periods.”
Various confirming studies may be referenced, such as that by Bhonsale and Saraswat (2012) analyzing late Quaternary sediments in the northeastern Indian Ocean.
3. The answer is choice “c” or “[(Natural Water Content – Plastic Limit) / Plasticity Index].” Thus: IL = (WN – PL) / PI
The plasticity index divided by the percent clay defines the “activity ratio.” Thus, choice (b) indicates: AR = PI / % clay.
Since the liquid limit minus the plastic limit defines the plasticity index, choice (a) becomes: LL – PL / PI = PI / PI = 1
Also, please recall that the “sensitivity” of a clay is defined by the ratio of its undisturbed strength to its remolded strength. “Quick clays” and “extra quick clays” have a “sensitivity’ values of 8 to more than 64! Some Norwegian and Canadian clays have “sensitivity” values of 500 to 1,000! Wow!
4. The answer is choice “c” or [S = 4 x – (10/3) y]. The proof follows:
“Cauchy’s Principle” relates the stress vector to the stress tensor via the unit normal vector. Thus: S = n * T
(3)
Then, from (1) and (2): n = (2/3) x – (2/3) y + (1/3) z
T =
7 0
-2
0 -2 5 0
0 4
we write: S = [2/3 -2/3 1/3] *
7 0
-2
0 -2 5 0
0 4
(1) (2)
(4)
S = [(14/3) + 0 - (2/3)] x + [0 - (10/3) + 0] y + [-(4/3) + 0 + (4/3)] z S = 4 x – (10/3) y
(5) Equation (5) is the answer to our problem and coincides with our choice “c”. Cool stuff, isn’t it? 5. The answer is choice “b” or “a klippe.”
A “fenster” describes an erosional “hole” or “window” in the overlying strata of the nappe exposing the underlying autoch- thonous rocks.
The terms “inselberg” and “monadnock” may be used interchangeably in describing an erosional remnant or residual hill or mountain standing above a plain.
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