Q: What are geologists?
What does a geologist do?
Geologists are what geologists do - pretty much the same thing as far as answering your two questions.
Geologists map the rocks and soils on the surface of the Earth, log (examine, analyze, and describe) cylindrical rock cores taken up from drill-holes, and sample sediment in streams and rivers. They try to figure out the ages of rocks and structures that the rocks are shaped (bent, folded, and faulted) into.
Some geologists measure geophysical fields and chemistry: they are called geophysicists and geochemists. They may do this by dropping sensitive instrument probes down deep drill-holes, and they may do this by making instrument measurements (or taking samples and chemically analyzing them) all over the Earth's surface. Fundamentally, they are interested in what's going on underneath the Earth's surface. With some experience, seeing what is on the surface or within the near surface regime can tell you what is going on much deeper than you can easily dig.
They do this in almost all cases for practical purposes:
- Where can oil be found?
- Where is the next mineral deposit so we can drive cars made of metals?
- When will the next-door volcano explode?
- When did the next-door fault rupture again?
- Why does my water taste like chemicals are in it?
As this last line of inquiry suggests, some geologists are specialists in groundwater: they are called hydrologists. They want to know where the water lies, where it is moving to and how fast, is it being recharged, and are there any pollutants in it?
The objective of all their work is to better understand:
- What the history of the landscape is,
- What lies underneath that landscape, and
- How do these things interact?
The end result is most clearly manifested in how well you live: Do you live in a heated or air/conditioned house? Do you drive a car?
To put things into blunt perspective, there was a political dog-fight going on in Tucson, Arizona once. Some people objected to a mining company developing a copper mine near (but not in) a national monument. The argument turned very rancorous, with political figures and newspapers being drawn into the fight. One day, bumper stickers appeared with large black letters on a yellow background. On top, in large type, it said "BAN MINING." Beneath that, in smaller letters, it said "Let the Bastards Freeze In The Dark."
Now, I'm probably more ecologically sensitive than most people, because I've seen first-hand the damage that uncontrolled mining has done to the deep Venezuelan jungle, where I lived for three years. However, I also have difficulty living with hypocrisy: people who complain about logging, while they themselves live in heated, wood-frame houses, bother me.
The answer, or course, lies in sustained, planned development: balancing everyone's needs including the aesthetic joy of hiking in a wilderness... but also ensuring the right to drive to the trail-head.