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Petroleum
Petroleum is a broad term that includes both
crude oil and natural gas. Crude oil is a thick, black
liquid mixture of naturally occurring hydrocarbons
(compounds containing hydrogen and carbon)
that forms from the buried remains of marine
organisms. Natural gas forms under similar
condi ons but is in a gaseous state.

Extrac ng Earth's Resources: Oil
Once oil or gas is found beneath earth's surface by geologists, it must be extracted.
Usually this is done by drilling through the rock to where the resource is trapped.
When the well is completed, oil or gas can flow into the well and the resources are
pumped up to the surface.
In oil companies, geologists are employed to iden fy the areas having oil or gas. Once
iden fied, the oil companies drill for oil. These geologists include stra graphers,
sedimentologists, and geophysicists. Many mes, however, dry holes are drilled and
geologists must move on to other loca ons.

Renewable resources can be Depleted
Some mes, however, renewable resources
can be depleted if they are used too fast!
Here are a few examples of how this can
happen:
 If an area undergoes severe deforesta on

and the soil erodes quickly, this will
deplete the land of fer le topsoil needed
to support plant growth, so trees and
shrubs cannot grow back.
 If trees and vegeta on are removed
without being replanted, this can have
effects on the land, air, and water. Common effects include runoff and water
quality.

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