EV 6
Over the last _____ years the Earth's magnetic field has _____.
2000, halved
Thanks to ocean floor coring we now have a very good chronology of global climate for roughly the last _____ years.
50 million
True or False. Diamonds are a rare resource only found in deep mines in South Africa.
False
True or False. Information on past climates is currently impossible to derive from ocean sediment data.
False
True or False. Manganese nodules are an important and economically viable source of metals.
False
True or False. Once an oilfield has been exploited for its resources in the traditional manner, there is little else to be done to extract more oil.
False
True or False. The climate record obtained from marine sediments goes back very close to the formation of the Earth 4.5 billion years ago.
False
The origin of the most abundant marine sediments is ______.
Land
True or False. Marine sediments give a much more continuous record of past climates that land sediments.
True
True or False. Remains of organisms found in sediment cores can give a close estimate of water temperature at the time of their deposit.
True
True or False. Sometimes the Earth can enter a critical stage that triggers rapid climate change.
True
True or False. The Earth is currently in a time of climate change.
True
True or False. There are tiny bits of magnetic material everywhere.
True
By "rapid climate change" scientists mean major change in _____.
a couple of decades
Traditional methods of oil and gas extraction routinely recover _____ of the resource from the field.
about half
In the equatorial Pacific there is little terrigenous sediment, but we would expect to find mostly ______ sediments, created by organisms.
biogenous
When shells or skeletons of animals fall to the ocean floor they form ______ sediment.
biogenous
Temporal information of the Earth's past climate comes from sediment _____.
cores
If the Earth's magnetic field reached zero, we would be at greater risk from _____.
cosmic rays
Micrometeorites impact the oceans, and although rare, form _____ sediments.
cosmogenous
Besides oil and gas, some economically impotent resources found in marine sediments include all of these except _____.
cretaceous iron ore
Huge boulders from land, found hundreds of miles out in the ocean, were carried there by _____.
glaciers
The basic principle of ocean coring uses a weighted _____ to collect samples.
hollow tube
In the middle of the southern Pacific, where there is little biologic activity, we would expect to find mostly _____ sediments, like manganese nodules.
hydrogenous or chemical
From the evidence in the sedimentary record, the Earth seems to be ______.
in a temperature range never before seen
Climatic scientists think that the _____, caused by Man, may be an important part of climate change.
increase in atmospheric carbon dioxide
According to the climatic record in sediments, right now we are in a climatic regime that _____.
is in a set of values never seen before
The evolution of marine sediment core retrieval since the mid-1800's has mostly increased the _____.
length of the core
The amount of _____ in shells in sediment cores can be used to determine _____ at the time of their formation.
magnesium, water temperature
Organic material buried in marine sediments can break down into smaller and smaller molecules through time and under heat and pressure, forming ______.
oil and gas
What process could possibly affect the maximum length [years] of the marine sedimentary record?
plate subduction and oceanic ridge activity
Because of environmental concerns about the impact of quarrying on land, more and more _____ will be taken from marine sediments in the future.
sand and gravel
The Deep Sea Drilling Project was originally begun to gain information on _____ from deep marine coring.
seafloor spreading
Ocean _______ can be considered the diary of the Earth's past history.
sediments
The longest climatic history that can be derived from marine sediments goes back _____ of years in some places.
tens of millions
Deposits of sediments from rivers and coastal erosion become ______ sediment.
terrigenous
Off the coast of Louisiana we would expect to find purely _____ sediments from the Mississippi River.
terrigenous
Volcanic action can add to the ocean's source of ______ sediment.
terrigenous
The Deep Drilling Project showed that using oxygen isotope ratios from sediment cores could estimate the amount of _____.
water in major ice caps