Geology

Geology means, literally, the study of the Earth. Explore this section to understand the structure of the Earth and its surface features, what causes earthquakes and tsunamis, and why volcanoes form and erupt. Learn about minerals, which form the building blocks of rocks, and how rocks are made and destroyed. Learn about Earth’s fascinating history, the variety of life forms which have roamed the surface over the millennia, and the dramatic changes that have happened over Earth’s long history.

You can get your own minerals and fossils, as well as the Fall 2010 issue of The Earth Scientist on Rocks and Minerals in our online store!

Scientists are still trying to learn how the <a href="/earth/interior/volcanism.html&dev=">volcanic</a> Hawaiian Islands formed. One theory is that they are made by upwelling plumes of <a href="/earth/interior/lava.html&dev=">lava</a> from the mantle inside the <a href="/earth/earth.html&dev=">Earth</a>. Scientists have obtained data that makes a strong case for the existence of a deep mantle plume below the Hawaiian islands.<p><small><em>Image Courtesy of Paul Johnson, University of Hawaii</em></small></p>Although we humans have never experienced fast <a href="/earth/climate/climate.html&dev=">global
warming</a>, our
planet has. And our planet keeps records of what happened. The oldest
records that the
<a href="/earth/earth.html&dev=">Earth</a> keeps
are in its
<a href="/earth/geology/sed_intro.html&dev=">rocks</a>.
In this image, <a href="/headline_universe/olpa/methane_28may08.html&dev=">geologists Chris von der Borch and Dave
Mrofka</a> collect
sediment samples in South Australia. These rocks hold clues to help
explain why climate changed abruptly 635 million years ago.<p><small><em>                    Courtesy of Martin Kennedy, UCR</em></small></p>Gold or Fool's Gold? There are two easy ways to tell Fool's Gold, the
  <a
  href="/earth/geology/min_intro.html&dev=">mineral</a>
  <a
  href="/earth/geology/min_pyrite.html&dev=">pyrite</a>,
  from real gold. First, pyrite leaves a black streak on a white tile whereas
  gold leaves, well, a gold streak. Also, pyrite is much harder than gold.
  Pyrite is made up of the <a
  href="/earth/geology/periodic_table.html&dev=">elements</a>
  iron (Fe) and sulfur (S). Both of these two elements are among the <a
  href="/earth/geology/crust_elements.html&dev=">eight
  most abundant</a> in the <a
  href="/earth/interior/earths_crust.html&dev=">Earth's
  crust</a>.<p><small><em> Courtesy of Corel</em></small></p>Sinkholes are <a href="/teacher_resources/main/frameworks/esl_bi8.html&dev=">natural hazards</a> in many places around the world. They are formed when water dissolves underlying <a href="/earth/Water/carbonates.html&dev=">limestone</a>, leading to collapse of the surface.  Hydrologic conditions such as a lack of rainfall, lowered water levels, or excessive rainfall can all contribute to sinkhole development. On 2/28/2013, a sinkhole suddenly developed under the house outside of Tampa, Florida, leading to the tragic death of its occupant, Jeff Bush.<p><small><em>Image courtesy of Southwest Florida Water Management District</em></small></p>A <a href="http://iopscience.iop.org/1748-9326/8/2/024035/article">study</a> of over 40,000 written entries in Irish Annals and ice core measurements shows a strong correlation between <a href="http://www.windows2universe.org/earth/interior/eruptions.html">volcanic eruptions</a> and extreme cold weather in Ireland over a 1200 year period, from 431 to 1649.  During this time up to 48 volcanic eruptions were identified in Greenland ice core records through deposition of volcanic sulfate in annual layers of ice. Find out more about <a href="http://www.windows2universe.org/earth/climate/geosphere_volcanoes_influence_on_climate.html">volcanoes and climate</a>.<p><small><em>Image Courtesy of Marco Fulle</em></small></p>How did life evolve on <a href="/earth/earth.html&dev=">Earth</a> during the <a href="/earth/past/Archean.html&dev=">Archean</a>, when the <a href="/sun/sun.html&dev=">Sun</a> was about 25% weaker than today?  The Earth should have been <a href="/earth/polar/cryosphere_glacier1.html&dev=">glaciated</a>, if <a href="/earth/climate/earth_greenhouse.html&dev=">greenhouse</a> gas concentration was the same as today.  <a href="http://www.manchester.ac.uk/aboutus/news/display/?id=10798">Researchers</a> studying the <a href="/physical_science/physics/atom_particle/isotope.html&dev=">isotopic</a> signatures of Earth's early atmosphere in <a href="/earth/geology/rocks_intro.html&dev=">rocks</a> from Northern Australia have ruled out high levels of <a href="/physical_science/chemistry/nitrogen_molecular.html&dev=">nitrogen</a> as a possible way to increase warming from <a href="/earth/Atmosphere/overview.html&dev=">atmospheric</a> <a href="/physical_science/chemistry/carbon_dioxide.html&dev=">carbon dioxide</a>.<p><small><em>Image courtesy of Manchester University</em></small></p>

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