Question	Answer	Comments
# 1	D	The oceanic crust consists primarily of the igneous rock basalt.
# 2	A	lateral offset is a characteristic of strike slip faults - the movement is parallel to the strike of the fault
# 3	B	Elastic deformation is recoverable once the stress is relaxed
# 4	B	Brittle failure occurs while the substance is undergoing elastic deformation
# 5	C	Recumbent folds are effectively lying on their side - the axial plane is horizontal
# 6	B	The oldest beds in an anticline are exposed at the core of the structure - as you go from the core to the limbs the rocks get younger.
# 7	D	All of these answers apply to the conditions or places where grabens (valleys) and horsts (uplifted blocks) can form
#8	C	Relative Dating requires that events be ranked from oldest to youngest
# 9	B	in a symmetrical anticline the beds dip equally away from the core of the structure
# 10	B	Note that the beds dip towards the core of the structure - a syncline and the dips are unequal on opposites sides - asymmetrical
# 11	A	The youngest rocks in a syncline are in the core of the structure - therefore if unit B is Silurian in age, unit C must be younger than Silurian - the Devonian is younger than the Silurian and the others are older.
# 12	A	Some of these features are produced under compression and others formed under tension - rocks formed under tension (at a divergent margin) may later be put under compression (subduction) ....
# 13	B	The dip of the fault plane is the difference between reverse and thrust faults - the sense of motion is the same for both
# 14	A	Therefore, the normal faults forming the graben must be younger than the folding event and normal faults form under tension
# 15	D	The Cambrian, Devonian and Permian Periods are part of the Paleozoic Era. The Cretaceous is part of the Mesozoic
# 16	B	Folding takes place under compression and divergent margins are under tension
# 17	E	All of these statements apply to Primary waves
# 18	C	S waves travel at a lower velocity than P waves (in the same material) but a liquid can not support the passage of an S wave
# 19	A	The Mercalli scale relies on obtaining information about the severity of damage or the sensations felt by those who were present
# 20	C	Dinosaurs became extinct at the end of the Cretaceous - about 65 million years age
# 21	C	Energy is released at the focus of an earthquake
# 22	B	The Epicenter is the point on the surface closest to the focus
# 23	B	A scarp is created initially on the upthrown side of the fault
# 24	A	The hanging wall moved down relative to the footwall moving up - a normal fault by definition
# 25	A	A record of a single event would begin with the arrival of a P wave which has the highest velocity, then the arrival of the S wave and finallly the arrival of the surface waves.
# 26	B	the generated longshore drift will deposit sediment at B.
# 27	B	S waves are propagated by displacements perpendicular to the direction of wave travel. Liquids will not support this kind of wave.
# 28	D	When a fault occurs energy is released - body waves form and travel away from the focus in all directions.
# 29	C	The bulk modulus measures how a substance resists changes in its volume - materials differ in how compressible they are.
# 30	B	Liquids do not resist a change in their shape - liquids will not support the transmission of S waves.
# 31	D	The shear modulus of the liquid is 0.0. The shear modulus is part of the numerator of the expression for the velocity of a P wave. The P wave would slow down
# 32	C	The numerator of the expression for the velocity of an S wave is the Shear Modulus - if the shear modulus goes to zero, the S wave will not be present.
# 33	A	P waves and S waves are generated at the focus of an event. P waves travel with a higher veolocity than S waves so the longer the time for travel, the greater the difference between the arrival times.
# 34	B	Each "step" on the Richter scale has an order of magnitude difference (power of 10). A magnitude 7 event is 10 times that of a magnitude 6.
# 35	B	Plates slide past one another at a transform boundary
# 36	E	All of these features form under compression.
# 37	A	The P wave shadow zone is caused by a reduction in veolocity when the P wave enters the liquid outer core. The S wave shadow zone is caused by the reduction to 0.0 when the S wave path enters the liquid outer core.
# 38	D	The Moho separates the rocks of the crust from those in the mantle. The boundary between lithosphere and asthenosphere separates a rigid from a weak, plastic, partially molten layer.
# 39	C	Currents generated in the outer, liquid iron-nickel core, while the Earth rotates, are thought to be responsible for the Earth's magnetic field. The Earth cannot have a dipole magnet because the magnet would loose its magnetic character when temperatures exceed its Curie point.
# 40	C	Natural magnets - magnetite - loose their magnetic character at temperatures about about 600 degrees C - about 20 kilometers beneath the surface of the Earth.
# 41	B	In periods of normal polarity the magnetic north pole is in the Northern Hemisphere - and vice versa.
# 42	A	When sea floor spreading is fast (10 or so cm per year) the magnetic strip is wider than it would be during slow (5 or so cm per year) spreading
# 43	D	basalts and gabbros form at divergent margins and comprise the oceanic crust
# 44	E	Island arcs (such as the Aleutian Islands) form where one piece of oceanic crust subducts beneath another
# 45	B	gravitational attraction is a function of the masses between the instrument and the center of the Earth and the distance between the instrument and the center of the Earth. If an area is underlain by denser material, the gravity anomaly will be greater.
# 46	A	An ophiolite is an old piece of sea floor.
# 47	E	shallow focus earthquakes would be expected at all of these boundaries.
# 48	A	this is a divergent boundary - spreading center
# 49	B	this is a transform - fault - boundary
# 50	C	a convergent boundary