Intro To Geology 200 Exam With Elaborated
Question & Answer 2024/2025
Name the four subsystems that constitute the Earth system. - CORRECT ANSWER-The four components
that constitute the Earth system:
a. atmosphere: the gaseous envelope surrounding the Earth.
b. hydrosphere: the water on or close to the surface of the Earth.
c. biosphere: the organic components.
d. geosphere: the inorganic components that include rock and other materials.
Which of the four subsystems do we concentrate on most in physical geology? - CORRECT ANSWER-In
physical geology we concentrate on the geosphere. Nonetheless, we will also examine how the other
components (or spheres) interact with the geosphere to explain processes that occur on and inside
Earth
What advantages does geothermal energy have over fossil fuels as a source of electric power
generation? What environmental problems are associated with the exploitation of geothermal energy? -
CORRECT ANSWER-As a source of electricity, geothermal energy offers some advantages over fossil fuels
because it has no emissions such as those associated with coal, oil, or natural gas. However, steam from
the hot water often contains hydrogen sulphide gas, which is toxic, and the hot water itself may contain
metal ions in solution such as lead and mercury, which are harmful to biological organisms. The
extraction of water for geothermal energy may also lead to ground subsidence, although pumping the
cooled water back into the ground may circumvent this. Finally, geothermal fluids are commonly highly
corrosive.
What is the difference between travertine and sinter? - CORRECT ANSWER-When hot water discharges
from the ground, it often has minerals crystallizing from solution as it exits. Under such circumstances,
deposits of calcite form travertine, while precipitating silica forms sinter. The type of precipitate is
determined by the geology of the subsurface.
What are geodes? - CORRECT ANSWER-Geodes are rock cavity infills with an exterior that comprises
layers of non-crystalline (amorphous) silica, and an interior that is often hollow and contains well-
formed crystals projecting inwards. Geodes form when crystal growth fills in the cavities.
,How do sinkholes form? - CORRECT ANSWER-Sinkholes are depressions on the landscape that form
when roofs of subterranean cavities collapse. Alternatively, sinkholes can form when downward
percolating groundwater enlarges cracks in soluble rocks such as limestone, rock salt (halite), or gypsum.
How do speleotherms form? - CORRECT ANSWER-Speleotherms are deposits of calcite that form from
dripping water in subterranean cavities. They essentially belong to two main categories: stalactites and
stalagmites. Stalactites are protrusions that hang from the roof of caves that form as calcite precipitates
from dripping water. They are often found aligned with cracks in the cave ceiling. Stalagmites, on the
other hand, are conical projections that form on the cave floor as water precipitates from dripping
water. Thus, stalactites grow downwards, while stalagmites grow upwards.
What is hard water? - CORRECT ANSWER-Hard water describes water with a high content of dissolved
ions, particularly calcium and magnesium. The calcium usually comes from the weathering of calcium-
bearing minerals such as calcite and dolomite. Magnesium is produced by the weathering of minerals
that contain magnesium, such as dolomite and ferromagnesium minerals.
What is the distinction between weathering and erosion? - CORRECT ANSWER-Weathering is the "in
place" disintegration and decomposition of unstable material at the Earth's surface; erosion is the
loosening and removal of material.
Why is artificial recharge sometimes carried out? How is this done? - CORRECT ANSWER-Extraction of
groundwater without adequate recharge can result in a negative water balance; that is, the water table
drops in elevation. A drop in the water table can result in a number of other problems such as ground
subsidence and compaction. To circumvent such problems, artificial recharge can be used to augment
natural recharge processes. Water used for artificial recharge includes flood waters and treated
industrial or domestic waste waters, which are collected and stored in specially-designed infiltration
ponds for percolating into the ground. Alternatively, water can be pumped into the ground as opposed
to letting it infiltrate from surface ponds.
What is saltwater intrusion? - CORRECT ANSWER-In coastal areas, freshwater usually occurs in the
ground as a distinct zone floating above a more dense saltwater zone. Saltwater intrusion refers to a
process that occurs when wells sunk to tap freshwater close to the coast are over-pumped such that the
freshwater lens thins. Saltwater then rises to fill the void left by the diminishing freshwater, and may
eventually be discharged by the well if pumping continues.
,Why will a mineral that formed deep below the Earth's surface tend to break down at the Earth's
surface? - CORRECT ANSWER-A mineral that formed deep below the Earth's surface is not at equilibrium
at the low pressure and temperature conditions at the Earth's surface. The mineral is unstable at the
Earth's surface and will have the tendency to break down to form other, more stable, minerals.
The outer layer of the Earth is called the crust. Identify the two types of crust and discuss the differences
between them. - CORRECT ANSWER-The two types of crust are oceanic crust and continental crust.
Oceanic crust is denser and thinner than continental crust.
List three surficial processes by which rock, originally elevated by the Earth's internal processes, wears
down. Can you think of any others? - CORRECT ANSWER-Three surficial processes by which rock that
was originally elevated by Earth internal processes wears down are flowing streams, waves, and glaciers.
Other processes include landslides and wind erosion
Identify two processes by which water returns to the atmosphere. What are the two mechanisms by
which water precipitated on land can return to the sea - CORRECT ANSWER-The two processes by which
water returns to the atmosphere are evaporation and transpiration. The two mechanisms by which
water precipitated on land can return to the sea are by surface runoff in streams and by percolation of
groundwater
Identify and discuss, briefly, the three major types of plate boundaries. - CORRECT ANSWER-The three
major types of plate boundaries are • divergent: the plates are separating. • convergent: plates are
moving together. • transform: plates are sliding past one another
Define each of the terms listed below.
a) Lithosphere
b) Asthenosphere
c) Atmosphere
d) Hydrosphere - CORRECT ANSWER-a. lithosphere: the relatively rigid crust and the uppermost part of
the mantle
b. asthenosphere: the part of the upper mantle that behaves plastically; the asthenosphere underlies
the solid lithosphere
c. atmosphere: the gaseous component of the Earth's surface fluids—air
d. hydrosphere: the water component of the Earth's surface fluids
, What is the distinction between lithified and cemented? - CORRECT ANSWER-A cemented rock has a
material (cement) that has been added between the grains to bind them together. A lithified rock is any
rock in which the grains do not easily separate. A rock may be lithified by cementation, compaction, or
recrystallization.
a. What is the current estimate of the age of the Earth?
b. According to recent theory, when did the first dinosaur appear, and when did dinosaurs become
extinct?
c. According to recent theory, when did the first humans appear on Earth? - CORRECT ANSWER-a. The
Earth is estimated to be about 4500 million (4.5 billion) years old.
b. The first dinosaurs are thought to have come into existence about 230 million years ago, and
dinosaurs are thought to have become extinct about 65 million years ago.
c. The first humans are thought to have appeared about three million years ago.
What percentage of geologic time does the last century account for? - CORRECT ANSWER-The last
century represents about 0.000045% of estimated geologic time.
Explain the principle of uniformitarianism. Use an example. - CORRECT ANSWER-The principle of
uniformitarianism is that the geological processes operating now are the same as those that operated in
the past; that is, the present is key to the past. An example of this principle is illustrated by rocks found
at the summit of the Canadian Rocky Mountains. We can see that some of the rocks are sedimentary
units that contain marine fossils. If the present is the key to the past, we should be able to conclude that
these rocks were formed below sea level just as rocks form today through the deposition of sediments
in a marine basin. The current elevation of the rocks must be a product of tectonic forces similar to
those that operate today at convergent plate boundaries. Thus, by observing and understanding
processes that are in operation today, we are able to explain phenomena that operated in the past.
List the names of the geological eras and periods in their correct relative time sequence - CORRECT
ANSWER-Cenozoic (quaternary, neogene, paleogene) 5mya-66mya
Mesozoic (cretaceous, jurassic, triassic) 252mya
Paleozoic (Permian, Pennsylvanian, Mississippian, Devonian, Silurian, Ordovician, Cambrian) 300mya,
400mya, 541mya
Precambrian (vast majority of time) 600mya, 3500mya, 4550mya
