actual exam questions
Gold placer deposits form by which of the following processes?
Gold grains settled out of river water sourced from eroding rocks that contained gold
Which isotopic ratio in ancient rocks has been used to support the timing of the evolution of photosynthesis?
13C/12C
Which side of a river channel is dominated by deposition?
point bar
Where are sediment grains coarsest along a stream?
center of channel
When did major extinction occur?
65 and 250 million years ago
At the beginning of which Era do fossils first occur with skeletal remains (hard parts) present within sedimentary rocks?
the Paleozoic era
How deep are the abyssal plains of the ocean floor?
about 4,000 meters deep (4 kilometers)
What is an example of a stream system with flashy water flow and steep gradients?
braided
Which river type has low gradients and continuous flow?
What was the name of the craton that created the North America?
Laurentia
Which of the following lists of Periods in the geologic time scale is correctly ordered from older to younger? Note that some may be missing in any of these lists.
Cambrian, Silurian, Permian, Jurassic
The ice presently covering both Antarctica and Greenland would, if melted, raise sea level by approximately ______.
70 to 80 m
When did most coal in the US get deposited?
Mississippian and Pennsylvanian
What was the primary composition of the primary atmosphere?
He and H
What is the salinity of the ocean?
35g/1000g water
3.5%
The half-life of a radioactive isotope?
the time it takes for the number of radioactive atoms in a mineral to be reduced to half of the initial number
The sinking of water at high latitudes, from the surface to the bottom of the ocean is termed thermohaline circulation and is promoted by _________.
higher salinity and colder temperature
What does thermal expansion of water do?
Increase sea level rise
What was the primary composition of the secondary atmosphere?
CO2, H20, N2
How much would the oceans rise if the greenland ice sheet melted?
6m
Which of the following correctly indicates the age in millions of years (Ma) for the boundaries between first the Precambrian and Paleozoic; then the Paleozoic and Mesozoic; and finally the Mesozoic and Cenozoic?
540, 250, 65
The addition of CO2 to the ocean makes the formation of CaCO3 in animals and plants __?
More difficult because of an increase in ocean acidity
What does NOT result in rising sea level?
melting sea ice
During what time period did we first see visible life?
Phanerozoic
What is the youngest part of the ocean?
Mid-ocean ridges