HISTORICAL GEOLOGY

A GLIMPSE INTO EARTH’S PAST: STUDY GUIDE

COMPILED FOR YOU BY KELLA RANDOLPH, BS, M.ED.

SCIENTISTS STUDY INFORMATION ABOUT THE EARTH’S HISTORY BY STUDYING ROCKS AND DATING THEM.

• The lifetime of the Earth has been subdivided by geologists into eras. This ‘geologic time scale’ is a sequential arrangement of time units as defined by geologists. Essentially it is based on two observations:

• In a stack of rock layers, the layers at the top must be younger than the layers at the bottom and,

• The presence of different fossils in each layer happens in order.

• These two observations enable scientists to tell the age of rocks containing fossils.

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PLACING ROCKS IN PROPER SEQUENCE OF FORMATION IS CALLED RELATIVE DATING

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Photograph above is of UNO students on field trip down in the Grand Canyon. In the canyon wall behind is a series of stacked sedimentary rocks.

RADIOMETRIC DATINGRadiometric dating is a complex procedure that measures the radioactive decay of certain minerals to accurately determine the age of many rocks.http://www.sciencechannel.com/tv-shows/greatest-discoveries/videos/100-greatest-discoveries-radiometric-dating.htm

RADIOMETRIC-DATING

• radiometric-dating • www.tech-faq.com maps.unomaha.edu phet.colorado.edu

FOSSILS NOT ONLY HELP WITH DETERMINING THE AGE OF ROCKS BUT ALSO INDICATE THE TYPE OF CLIMATE AND ENVIRONMENT

Historical Geology Lab Fossil Practical #2 Images facultyweb.wcjc.edu

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CLASS: Trilobata - the trilobites (CAMBRIAN to PERMIAN) Trilobite

WHAT IS THE GEOLOGIC TIME SCALE? It is a time line dividing the earth’s history into units representing millions of years

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THE FIRST TYPES OF ROCKS PRODUCED DURING THE PRECAMBRIAN WERE IGNEOUS EXTRUSIVE ROCKS.WSC10SCIENCE.WIKISPACES.COM

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THE OLDEST FOSSILS ARE DATED AROUND 3,800 MILLION YEARS AGO.

• Ancient Fossil Bacteria : Pictured above are two kinds cyanobacteria from the Bitter Springs chert of central Australia, a site dating to the Late Proterozoic, about 850 million years old. On the left is a colonial chroococcalean form, and on the right is the filamentous Palaeolyngbya. www.ucmp.berkeley.edu

BITTER SPRINGS CHERT OF CENTRAL AUSTRALIA• (850-million-year-old) • Bitter Springs chert of central Australia• www2.fiu.edu

CYANOBACTERIA ARE STILL AROUND

• Cyanobacteria are aquatic and photosynthetic, that is, they live in the water, and can manufacture their own food. Because they are bacteria, they are quite small and usually unicellular, though they often grow in colonies large enough to see. They have the distinction of being the oldest known fossils, more than 3.5 billion years old, in fact! It may surprise you then to know that the cyanobacteria are still around; they are one of the largest and most important groups of bacteria on earth. Images of Nostoc and Oscillatoria provided by the University of Wisconsin Botanical Images Collection.

WHAT THREE ERAS IS THE PHANEROZOIC EON DIVIDED INTO?

PaleozoicMesozoic Cenozoic

THE PHANEROZOIC EON SPANS 542 MILLION YEARS.EDUCATION-PORTAL.COM

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DURING THE CAMBRIAN PERIOD OCEANS AND SHALLOW SEAS COVERED MUCH OF THE EARTH.MUCHOLDERTHEN.TUMBLR.COM WWW.LIVESCIENCE.COM

THE CLIMATE BECAME MORE STABILIZING DURING THE SILURIAN PERIOD.

UNDERWATER LIFE THRIVED DURING THE SILURIAN PERIOD, 443 MILLION YEARS ...WWW.LIVESCIENCE.COM

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DURING THE DEVONIAN PERIOD THE FIRST WINGLESS INSECTS , TREES AND FORESTS APPEARED.

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IT IS THOUGHT THAT OVER 90% OF MARINE SPECIES BECAME EXTINCT AT THE END OF THE PERMIAN PERIOD.

OLDEST FOSSIL SEA TURTLE DISCOVERED PHYS.ORG

AT 55 MILLION YEARS OLD, IT IS THE OLDEST KNOWN FOSSIL OF A PRIMATEWWW.CSMONITOR.COM

THE CLIMATE DURING THE TRIASSIC PERIOD WAS MOSTLY INFLUENCED BY TECTONIC EVENTS.

WWW.HAIKUDECK.COM GEOLOGICALTIMEPERIODS.BLOGSPOT.COM

THE JURASSIC PERIOD HAD ABUNDANT LIFE FORMS (DINOSAURS).

• Jurassic Period• Animals And jurassic periods.

• galleryhip.com

THE TYRANNOSAURUS REX HAD JAW MUSCLES THAT WERE CAPABLE OF EATING UP TO 500 POUNDS OF MEAT AND BONES IN ONE BITE.

• prehistoricworldofyajur.wordpress.com

WHAT DO SCIENTISTS BELIEVE IS THE RESPONSIBLE FOR THE EXTINCTION OF 60% OF THE WORLD’S SPECIES DURING THE CRETACEOUS PERIOD?

An asteroid hitting the Earth may have created such a thick cloud of dust that the sunlight could not penetrate. It was cold and dark. Most plants and animals died.

WHAT IMPACTS HAVE HUMANS HAD ON THE GEOLOGY OF THE EARTH? Contributing to extinction of many species, deforestation, mining, pollution, etc. 

CARELESS MISUSE OF THE LAND AND WATER RESULT IN POLLUTION AND LOSS OF HABITAT. SLIDESHARE.NET NICKEL MINING POLLUTION GALLERYHIP.COM

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HOW GEOLOGY WORKED WITH BIOLOGY TO MAKE LIFE ON EARTH

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THIS PLANET EARTHIt is our only home. Protect it, care for it, and enjoy the many wonderful and beautiful things it has to offer.

Acquired January 4, 2012 download large image (11

MB, JPEG ...earthobservatory.nasa.gov