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