10 Questions
What percentage of Earth's surface is covered by oceans?
70 percent
What is the average salt content of ocean water?
35 parts per thousand
How much salt per cubic mile of seawater is there in the ocean?
120 million tons
What causes rain to become slightly acidic as it forms and falls through the air?
Absorption of carbon dioxide
How does ocean water accumulate salt and other dissolved minerals?
From eroding rocks and picking up dissolved minerals
Edmond Halley suggested that the salinity of seawater could serve as a kind of ______ that could be used to determine the age of the ocean
clock
John Joly came up with an estimate of 90 million years for the age of the ocean using Halley's ______
scheme
Halley reasoned that dividing the total volume of ocean water by the rate at which salt was deposited in the ocean would show how long it had taken for the ocean to reach its current level of ______
salinity
More-advanced techniques later revealed the estimate of 90 million years to be a major ______
underestimate
Halley had failed to account for the fact that some sea salt becomes ______
sequestered
Study Notes
Salt Deposition in the Sea
- In 1715, British astronomer Edmond Halley proposed that salt was gradually deposited in the sea by rivers.
- Halley suggested that the salinity of seawater could be used as a clock to determine the age of the ocean and, by extension, the Earth.
- He proposed that dividing the total volume of ocean water by the rate of salt deposition would reveal the time it took for the ocean to reach its current level of salinity.
Early Estimation of the Ocean's Age
- In 1899, Irish physicist John Joly attempted to calculate the age of the ocean using Halley's method.
- Joly estimated the age of the ocean to be around 90 million years.
- Later, more advanced techniques revealed that this estimate was a major underestimate, and the actual age of the ocean is around four billion years.
Flaws in Halley's Scheme
- Halley's method had a significant flaw: it failed to account for the sequestration of some sea salt.
- This oversight compromised the accuracy of Halley's proposed method for determining the age of the ocean.
Test your knowledge of Earth's water bodies and their properties with this quiz on oceans and their characteristics. From the largest ocean to the salinity of seawater, challenge yourself with questions about the vast bodies of water that dominate our planet.
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