Geologic Time



Name _______________________

Geologic Time

Chapter 17 section 1

(This is transcribed from a Prentice Hall

read only slide show.)

Geologic Time Scale:

|Slide Number |Information |

|761 |To understand ________, it is important to realize that our ______________________. |

|762 |Modern methods of ______________________ put Earth’s age at _________________________. |

|763 |This immense time span is hard to comprehend. Guess about how long it would take just |

| |to count to 4.5 billion if you could count one number per second without stopping. |

| |__________ |

|764 |An appreciation for the magnitude of geologic time is important because many of |

| |_________________ ________________ that __________________ are needed for significant |

| |changes to occur. |

|765 |It took _______________________ to create these mountains and it will take |

| |_______________ ________________________________. |

|766 |Geologists have divided all of Earth history into units of varying magnitude. Together|

| |they comprise ____________________. |

|767[pic] |The _________________ provides a framework for arranging events of the |

| |_________________. |

|768 |_______ represents the _________________ |

| |_______. |

|769[pic] |The _________ that began about _____________ is called the Phanerozoic, |

| |__________________. |

|770 |The _________________________________ |

| |of Phanerozoic eon contain an ______________ __________________________. |

|771 |The Phanerozoic eon is divided into units called ______. |

|772 |The era names refer to import differences in dominant life-forms. |

| |______zoic refers to ancient life. Example Trilobite fossils. |

| |_____zoic refers to middle life. |

| |_____zoic refers to recent life. |

|773 |Each era is divided into smaller units called _________. |

|774 |The changing fossil record also played an important part in establishing each of the |

| |periods. |

|775 |Periods may be divided into epochs. Seven epochs are names for the periods of the |

| |Cenozoic era. |

|776 |The epochs of other periods usually are just _____ |

| |______________________________. |

|777 |The _____________________, which ended just 10,000 years ago, coincides with a time |

| |span commonly known ________________________. |

|778 |The detail on the time scale does not begin until about 540 million years ago, the date|

| |for the _____ |

| |______________________________. |

|779 |The vast expanse of time prior to the Cambrian Period is divided into three eons-the |

| |_______, the ___________, and the _______________. |

|780[pic] |This greater than 4 billion-year span is also commonly called the ________________. |

|781 |About what percent of Earth’s 4.5 billion-year history is represented by Precambrian |

| |time? _____ |

|782 |Why are the eons of Precambrian time not divided into numerous eras and periods? |

|783 |One reason is that __________________ was soft-bodied and therefore the fossil record |

| |is meager compared to the Phanerozoic eon. |

|784 |In addition, much of the Precambrian rock record is buried beneath younger rocks and/or|

| |altered by metamorphism. |

| |The Grand Canyon’s ancient Vishnu schist is buried beneath a huge pile of Paleozoic |

| |rocks. |

|785 |Which is the greatest expanse of time? _______ |

|786 |Which is a subdivision of an epoch? ___________ |

|787 |Mesozoic is an example of ________. |

|788 |Eons are divided into these _________. |

|789 |Which is the smallest time span on the geologic time scale? _______ |

|790 |Cambrian and Jurassic are examples of ________. |

|791 |The age of the Earth is about: ________________ |

|792 |The Phanerozoic eon began about years ago. |

|793 |We are presently living in the ____________ era. |

|794 |The Hadean, Archean, and Proterozoic are: ______ |

| |_______________________________________ |

| |__________________________________. |

|795 |Which era of the Phanerozoic eon has the most periods? _________________ |

|796 |Eocene, Pleistocene, and Holocene are examples of: __________ |

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