ANSWERS TO “TEST YOUR KNOWLEDGE” ON PAGE 36


Answers: 1. The answer is choice “b” or “klippe.”


In geoscience literature the term “klippe” has been used to describe three different types of standard tectonic features:


a) An overthrust or allochthonous klippe (as described in this example). b) An autochthonous klippe, like the exposed crest of a mushroom-shaped fold. c) A piercement-type klippe or diapiric structure.


Guyots are flat-topped sea mounts.


Barchans are crescent-shaped sand dunes with horns pointing downwind. Tombolos are sand bars joining an island to the mainland.


2. The answer is choice “a” or “echinodermata.” The description indicates “crinoids” which are related to sea cucumbers, sea urchins, starfishes and brittle stars.


Marine arthropods are crustaceans including shrimps, crabs, lobsters and the extinct trilobites.


Marine coelenterates (phyla Cnidaria, Ctenophora) include corals, sea fans and anemones, jellies and sea pens.


Chordates include the vertebrates. This phylum of animals, during some period of their life cycle, possess a notochord (cartilaginous skeletal rod), a dorsal nerve chord, pharyngeal slits, an endostyle (mucus-secreting pha- ryngeal organ) and post-anal tail.


3. The answer is choice “d” or “Crustal deformation involving basement rock and deep-seated faults.” This contrasts with “thin-skinned tectonics” describing deformation related to shallow thrusts and folded strata comprising the sedimentary rock cover and not the underlying basement.


4. The answer is choice “c” or “Mercury” with an average density of 5.43 gcm-3. g


5. The answer is choice “a” or “[3.39 * 10-2 meters/second2].” The proof follows


Given: R = 6,400 kilometers = 6.4 * 106 meters T = 24 hours = 24 * 60 * 60 = 8.64 x 104 seconds


(1) (2)


Then:   4 seconds) -5 radians/second ac2


Substituting (1) and (5) into (6), we obtain: ac = 6.4 x 106 meters * (7.27 * 10-5 radians/second)2 ac = 3.39 * 10-2 meters/second2


Jupiter, Neptune and Mars have average densities of 1.33 gcm-3, 1.64 gcm-3 and 3.93 gcm-3, respectively.


g


(4) (5) (6)


(7) (8)


Equation (8) is the answer to our problem, or the centripetal acceleration of a point on the Earth’s surface at the equator.


38 TPG • Jul.Aug.Sep 2021


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