Flashcards in EXAM 1 Questions Deck (88):
Why do geologists refer to the last 2 to 3 million years of Earth’s history as the “Modern Ice Age, i.e. how has the last 2 to 3 million years of Earth’s history differed from earlier history?
What evidence exists to show that Earth’s climate became much colder ~3 million years ago?
The cold Arctic region effectively cools the world: What keeps the Arctic region cold today?
How and why were large-scale ocean currents different prior to ~3 million years ago than they are today?
For any given place on Earth, what are some of the factors that control climate?
Major ice ages, similar to the one we live in today, have occurred several times during Earth’s history. Did the conditions leading to these ice ages evolve relatively slowly or quickly?
During the ice age we live in now, what has controlled the cycling between Glacial and Interglacial periods?
At the subatomic level, what is unique to each of the known elements in the Periodic Table?
Different number of protons.
How does one isotope of oxygen differ from another isotope of oxygen?
Number of neutrons
Explain why fractionation takes place when water is evaporated from the ocean.
Fractionation applies to a process that changes the relative amount of isotopes in a water. The proportion of O16 and O18 in water. Process is evaporation (dependent on temp and mass of molecule)
How does the percentage of H218O occurring in snow or rain differ when it’s warm vs when it’s cold?
At any place in a long ice core retrieved from the Greenland Ice Sheet, how do geologists know how old the ice is?
When did the last interglacial period, the one we’re living in now, begin?
Was the change from the last glacial period to the current interglacial period occur smoothly over a long period of time or abruptly over a relatively short period of time?
Compare the stability of Earth’s temperature during the interglacial period we live in (the last 10,000 years) and the last glacial period (~120,000 to 10,000 years).
What are the necessary conditions for glacier to form?
What are some of the processes occurring as snow changes to glacial ice?
As snow changes to glacial ice, its density increases. What is the principle process causing the density to increase?
Compaction from greater weight of snow. the snow is mostly air which is forced out.
What are some of the ways that continental ice sheets differ from alpine glaciers?
If alpine glaciers move down the valleys they lie in, what determines the direction that continental ice sheets move?
What is the source of energy causing glaciers to move?
Where do alpine (or valley) glaciers move most quickly?
What are the different processes that contribute to the motion of glaciers?
What is the evidence, the frequent observation on rock surfaces, that glaciers are capable of sliding along their bases?
What is the evidence, the frequent observation within glaciers, that glaciers are capable of deforming in a ductile manner (smoothly, without cracking)?
What is the evidence, the frequent observation within glaciers, that glacier behave in a brittle manner (they crack and break) near their surfaces?
What is the difference between the accumulation zone and the ablation zones on glaciers?
What is the relationship between the mass balance of a glacier and the position of that glacier’s terminus with time?
Compare/contrast the processes of glacial abrasion and glacial quarrying.
How can roches moutonneé be used to determine what direction a glacier was flowing?
How and why are the shapes of valleys eroded by glaciers different from the shapes of valleys eroded by streams?
How do hanging valleys form?
What are some of the characteristic features of glacial cirques?
Cirques are generally eroded in the accumulation zone/equilibrium line/ablation zone of glaciers (choose one).
How does a glacial horn differ from a glacial arêtes?
What is similar and what is different about the processes producing glacial horns and glacial arêtes?
Give a definition of glacial till.
In New England, where, relative to the ice sheet that used to cover the area, was most till deposited?
What is a glacial erratic?
How can erratics be used to help determine the direction that glaciers flowed?
Erratics are uplifted rocks from different areas, these rocks can be traced to their original location.
What are two processes that can produce end moraines?
What are some of the attributes of moraines that make them distinctive, that allow you to see them?
How do medial moraines form?
How do glacial kettles form?
How is glacial outwash different from glacial till?
How are sediments classified by size?
Relative to the direction that a glacier is flowing, describe the shape of drumlins produced by that flowing ice.
Drumlins are elongated asymmetrical hills with a gradual slope faces downstream. Step end faces glacier. The long axis is parallel to the flow of the glacier.
What kind of sediment occurs in an esker?
In the ablation zone of glaciers, what happens to water generated by melting snow and ice? Describe the pathways it follows across and through a glacier.
What can happen to the speed of a glacier as more water reaches its base?
What are some of the feedback mechanisms that can cause an ice sheet to rapidly disintegrate?
Climate is warming, more snow/ice is melting than falling. Water moves to base and moves it faster downgrade to ocean.
What is the evidence you would look for to know that a lake used to exist somewhere?
During what time frame, approximately, was the Laurentide ice sheet retreating across New England?
At it's maximum extent about 25,000 years ago, 13,000 years is was near Champlain Valley
Many glacial lakes occurred in Vermont and elsewhere in New England as the ice sheet was retreating. What were the geographical constraints that allowed lakes to form in some areas?
A closed basin is needed for the lake to form. Naturally occurring rock dam was formed at the north end of the lake.
How can we determine the elevation of the glacial lakes that used to exist here?
Why is it that the shorelines of these old glacial lakes, that were horizontal when they formed, are now tilted upwards to the northwest?
When the land surface sinks as an ice sheet grows on the land surface, what is flowing out of the way and where does it go?
Compare the strength of the Lithosphere vs the Asthenosphere.
Lithosphere is a stiff and strong (sinks), Asthenosphere is weaker (fluid and viscus).
Isostatic changes to the land surface in response to adding or subtracting the load of a continental ice sheet are relatively fast or slow? What processes govern the speed?
Where, approximately, was the Laurentide ice sheet when the Champlain Sea formed?
How was it possible that the much of the Champlain valley and adjacent St Lawrence valley were flooded with sea water for several thousand years following the retreat of the ice sheet?
What evidence exists in sediments occurring in the Champlain valley that the area was flooded with salt water?
What is meant by the term “Periglacial?”
At the edge of a glacier environment (does not need to be a glacier) avg. temp -5C. permafrost. Conditions for glaciers to from is not there.
What landforms frequently develop in areas with permafrost?
Patterned Land: Polygonal Patterns formed from ice melting in the soil and cracking. Very boggy areas and wet
What frequently occurs to buildings and forests in areas where permafrost is melting?
How is it that changes in climate are recorded in the changing temperature with depth in a hole drilled into permafrost?
The permafrost layer is slowly changed by the climate and therefore the temperature profile is gradually slopped instead of jagged like air temp.
Why can long-term records of the size of glaciers be used as a measure of climate change?
Why were Scandinavians able to settle in Greenland beginning in 985 AD?
Why are temperature measurements of permafrost a better measure of climate change than temperature measurements in air?
What is the “active layer” in permafrost regions?
The top meter or so that melts in the summer and allows plants to grow.
Why may melting permafrost accelerate global warming?
Release methane and other greenhouse gases from decomposing plant material underneath.
How can you tell the difference between sea ice that’s seasonal and sea ice that’s permanent?
Seasonal sea ice has more salt in it. Permanent sea ice forces the salt out.
What is “albedo” and how does it differ between snow, ice, land, and water?
Is the reflectivity of a surface to sunlight. Snow (0.01) has a high albedo, ice (0.1) is lower, followed by land (0.3-0.8) and water (0.9)
Compare how easily visible light passes through oxygen, nitrogen, carbon dioxide, water vapor, and methane.
Compare how easily infrared radiation passes through oxygen, nitrogen, carbon dioxide, water vapor, and methane.
Passes mostly through Oxygen, Nitrogen. Reflected or absorbed by CO2, water vapor and methane. Tyndal Discovery 1850
Why does the Keeling Curve make annual up and down swings?
The Keeling Curve shows the amount of CO2 in the atmosphere, the swings result from summer and winter. CO2 is higher in the winter because plants are hibernating.
What processes cause barrier islands to move as relative sea level rises (or falls)?
As one part shrinks another part moves by erosion along/ toward mainland.
What processes can cause the volume of water in the oceans to change?
What processes can cause the land surface to rise or fall?
Explain the different relative age dating principals.
When describing radioactive decay, what is the difference between a “parent” and “daughter” isotope?
What is meant by the “half life” of a radioactive isotope?
How can zircon crystals be used to date rocks?
Newly grown crystals only include uranium, as it ages the uranium breaks down into lead. The proportion of U to Pb can be used to calc age.
Where and how is Carbon-14 generated?
In the atmosphere by cosmic rays hitting atoms. Stray neutrons hit nitrogen, and then a proton comes out causing the nitrogen to become Carbon-14
How is Carbon-14 incorporated into living organisms?
Carbon-14 forms with O2 to make CO2 that is used by plants and animals
Why can’t Carbon-14 be used to date materials that are older than ~50,000 years?
C-14 has a short half life, after 10 half lives the amount left is undetectable. Coal is carbon rich but millions of years old, no C-14 left.
When did Earth form? What has been dated to come up with this date?
4.56 Billion years ago. Zircon Crystals.