Question

Shorter geological periods may be estimated by measuring the rate at which:

Options

• Uranium changes into lead

• Rubidium-87 changes into strontium

• Radioactive potassium-40 changes into argon

• Waterfalls retreat upstream as they erode bedrock

Answer 1

Shorter geological periods may be estimated by measuring the rate at which waterfalls retreat upstream as they erode bedrock. Such physical methods estimate shorter durations compared with long-term radioactive dating methods.