ES 10 Geologic Principles;	Test 1;		October 25, 1994;	Alfred Hochstaedter

1. a) (4 pts) Besides the atmosphere, what are the things that make Earth different from the other
terrestrial planets (Mercury, Venus, Mars); i.e., why is Earth the ŌSpecial PlanetĶ?


b) (4 pts) Now for the atmosphere; what are the things that make the EarthÕs atmosphere different
from that of the other terrestrial planets?

c) What is the definition of the Gaia Hypothesis?

d) (4 pts) How do the various things you listed in part a) interact with each other to regulate the
average temperature of the Earth.


e) (4 pts) What implications do the Gaia Hypothesis have for the search for extraterrestrial life,
especially those proposals that involve manned search parties?


f) (no credit; answer only if you have time) What do you think about all this Gaia stuff? What are
the strengths and weaknesses? IÕm really interested in what you think.

2. a) (9 pts) Please use labelled diagrams to help explain both compositional and physical layering.

b) (3 pts) What is the difference between the crust and the lithosphere?


c) (4 pts) What is the definition of Uniformitarianism?

d) (4 pts) What is the evidence for Uniformitarianism on Earth?

3. a) (10 pts) What are the important geologic features observed in this slide (Grand Canyon), and
what do they indicate about Earth History in this particular spot?


b) (10 pts) Fill in the blanks of this geologic time scale.

4. a) (2 pts) Describe the differences in shape between shield volcanoes and strato-volcanoes (use
diagrams if you like).


b) (4 pts) What kind of eruptions do these two kinds of volcanoes commonly have, and what is
the composition of the rocks that commonly come out of these volcanoes?


c) (4pts) What are the controlling factors that influence the kind of eruption and the shape of the
volcanoes, and how do they work? In other words, how or why does this controlling factor work?

d) (4 pts) Draw BowenÕs Reaction Series here.

e) (6 pts) What is crystal fractionation, and what is it about minerals crystallizing from magmas
that makes it work. Use a phase diagram or the mass balance equation
(Ctotal=CsolidXsolid+Cliquid Xliquid  and  Xliquid + Xsolid = 1) as an example to
help explain your answer. (Either an example of a phase diagram or the equation will do here; you
neednÕt use both.)

5.a) (5 pts) Start by drawing a picture of a 14C atom, labelling all of the protons, neutrons, and
electrons (in their appropriate energy shells; remember that the innermost shell holds only two
electrons, while the next one holds a maximum of eight electrons). In the space beside your
drawing you define the atomic number (which is 6 for Carbon) and the mass number (or the
atomic weight; use whichever one you remember). What is the mass number for 14C?



b) (5 pts) Explain the difference between ionic and covalent bonding in minerals. As an example,
draw covalent bonds between a Si atom and four Oxygen atoms to form a silicate anion (Silica has
4 electrons and Oxygen has 6 electrons in their outermost energy shells, which are all you need
worry about here). Beside your drawing, explain how you figure out what the charge would be if
this complex anion were to later form an ionic bond with some other cations.

c) (5 pts) Using a diagram, explain how Beta decay works to transform 14C to 14N. Be sure to
explain the changes (or lack of) in mass number and atomic number during the transformation.




d) (5 pts) Turns out he had measured 10 quadrillion 14C atoms in the pumpkin at the beginning of
party and knows that there are only 5 quadrillion 14C atoms in the pumpkin now. You volunteer
that the half life of 14C is 5700 years. How long have you been at the party? You decide itÕs time
to be heading home.