DK Earth: Earth Sciences
Earth science is the study of our planet’s physical characteristics, from earthquakes to raindrops, and floods to fossils. It contains many branches, such as GEOLOGY and oceanography (the study of the world’s oceans).
Earth science affects our everyday lives. For example, meteorologists study the weather and watch for dangerous storms. Hydrologists study water and warn of floods. Seismologists study earthquakes and try to predict where they will strike. Geologists study rocks and help to locate useful minerals.
Earth scientists mainly work “in the field”—climbing mountains, exploring the seabed, crawling through caves, or wading in swamps. They measure and collect samples (such as rocks or river water), then they record their findings on charts and maps.
Geology is the study of the rocks that form the planet’s surface. Geologists examine rocks to find out about the history of the Earth and how Earth was formed.
Rocks are dated using several methods. Geologists called stratigraphers study the distribution and order of rock layers, or strata. The youngest rocks are usually found in layers near the surface; older rocks lie deeper below. Some rocks contain radioactive elements that can be dated because they decay, or change, at a particular rate.
Fossils (remains or prints of living things preserved in certain types of rock) tell scientists the relative age of that rock—that is, whether it is older or younger than other rocks. This helps scientists to figure out the history of rock formation in different areas. The first fossils were formed around 3,600 million years ago.