ABSTRACT
Bifocal lenses allow people with vision problems to see both near and far objects. In geology, a view of rare events far away in space and time gives us the ability and perspective to focus on their possible occurrence and impact in our nearby space and in future times. When meteorites land on the Earth, they make depressions called impact craters. We can go into the field—geology slang for going out into the world and making measurements—and look at various young and old craters, measure their ages, make estimates of the size of the meteorite that caused a particular crater. Infer the frequency with which meteorites of various sizes hit the Earth. Farmers have been forced to use artificial fertilizers because natural fertilizers are no longer replenished by annual floods. Lands that are newly irrigated by the stored and diverted waters do not drain well.
