Old Earth Ministries Online Earth History Curriculum
Presented by Old Earth Ministries (We Believe in an Old Earth...and God!)
This curriculum is presented free of charge for use by homeschooling families and schools.
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Chapter 3 - The Cambrian Period
Lesson 14: Cambrian Overview
The Cambrian is the first geological period of the Paleozoic era, lasting from 542 ± 0.3 million years ago to 488.3 ± 1.7 million years ago; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the classical name for Wales, where Britain's Cambrian rocks are best exposed.
The Cambrian was a relatively warm period, with temperature averages about 7 degrees C warmer than they are today. Although it was warm, there is evidence of glaciers being present in the Cambrian. The earth's atmosphere during this time contained about 13 percent oxygen (compared to 21 percent today). The greenhouse gas CO2 content of the atmosphere was 4500 ppm, which is more than 11 times the level of today. The temperature average during the Cambrian was 7° C higher than today.
Chapter 3: The Cambrian Period
Cambrian Fast Facts
Started: 542 Ma
Ended: 488.3 Ma
Duration: 53.7 Million Years
Preceded By: Ediacaran Period
Followed By: Ordovician Period
|Mean atmospheric O2 content over period duration||
ca. 12.5 Vol %
(63 % of modern level)
|Mean atmospheric CO2 content over period duration||
(16 times pre-industrial level)
|Mean surface temperature over period duration||
ca. 21 °C
(7 °C above modern level)
|Sea level (above present day)||Rising steadily from 30m to 90m|
Reconstructions of Cambrian geography
that a global supercontinent,
Pannotia, was in the process of breaking up,
separated from the main mass of the
Gondwana supercontinent to form isolated
landmasses. Most continental land mass was
clustered in the southern hemisphere.
exists for the stratigraphy of the
Cambrian period. The supposedly
international (i.e. Western) ICS scheme is in a state of flux, and does not
yet have any firmly established internal boundaries, although it has set a
stratotype section for the base of the Cambrian, dated quite accurately to
542 ± 0.3 million years ago. In contrast, the Russians and many Chinese
scientists prefer a different scheme; since the most significant exposure of
Cambrian strata lies in these countries, they are arguably better placed to
is unique in its unusually high proportion of
lagerstätte. These are sites of exceptional
preservation, where 'soft' parts of organisms are preserved as well as their
more resistant shells. This means that, paradoxically, our understanding of
the Cambrian life surpasses that of later periods.
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