The Cambrian period is the geologic age which marks the end of the Paleozoic era. It began after the eras and eons collectively referred to as the Precambrian. Cambrian period is estimated to have begun before 550 ~ 570 million years, but its exact beginning is still unmeasurable, so it is generally estimated by the appearance of the sea creatures, which have left the unexplained limestone shells on the geologic record. The name ‘Cambrian’ is derived from the English geologist, Adam Sedgwick; he named Cambrian by deriving from the province of Wales in 1835, which is also called Cambria.
This system is subdivided into continuous units: Comrie unit, Saint David unit, and Meriones unit in each low, middle, and upper Cambrian system. However, the relative eras are not settled appropriately due to the fossils. The fourth unit of Cambrian system, Tremadoc unit, is considered as the last unit in the Cambrian period or the first unit of the Ordovician period. The boundary between Cambrian and Ordovician period is not settled yet globally, but the Tremadoc unit is commonly considered as one of the units that took place during the Ordovician era. 
Ecologist Jeffrey Levinton wrote an impressive review about the Cambrian Explosion in the journal, BioScience, which includes two mysteries of evolutionary reflections.
One of the reflections Levinton provided is that, even if he proposed some evolutionary drafts, the sudden appearance of the various bodies that operates in the Cambrian strata has nothing to do with the process of the already-known evolutionary outcome.
He accepted that what evolutionism guesses about the period when the first animal appeared, and a similarity of the order of DNA or protein among the organisms are paradoxical. Evolutionary geologist, who accept only old strata, evaluated the Cambrian rocks and dated them at about 542 million years.
According to their data, extreme variations of biologic formations have occurred rapidly at the lowest sedimentary strata. After Levinton had checked the fossil and molecular clock data, he said,
|“||The presence of genomic complexity, right at the dawn of bilaterian animal life [i.e., animals with bilateral symmetry], is inescapable.||”|
Levinton said that all the important experiments estimated the rocks formed over 586 million years to 1200 million years (It is claimed that the lack of exact dating is due to the inaccuracy of the molecular clock.) These broad dating estimates strengthen Levinton’s assertion, that the hypothesis of molecular evolution models impact critically to the dating estimates by the molecular clock, so that they can’t be trustworthy.
Levinton had proposed that biologic dating should follow the authority of geologic dating, but creation scientists proposed that evolutionary hypotheses impact is so significant that they made the two dating (biologic dating and evolutionary dating) distrustful.
About the accord with major evolutionary models, Levinton said, “We only hope that more valuable evidences will be discovered.” Even with the dearth of fossil evidences, as well as even with the discordance between fossil data and the molecular clock, a number of scientists hang on to the evolutionary descriptions.
Creation models however, don't feel the need of the discovery of more valuable evidence. The evidence that creatures, which have the perfect fossilized forms appear suddenly at the bottom of the strata have an accordance with the Biblical record, which says that all the creatures were created during the Creation period, not over million years. Discovering of sea creature fossils at the sea layer of the thick accumulated strata on the all the lands, also has an accordance with the Genesis Flood record, which is saying that there was the Global Flood. Genesis 7:6-10 show that there was a flood on the earth;
6 Noah was six hundred years old when the floodwaters came on the earth. 7 And Noah and his sons and his wife and his sons' wives entered the ark to escape the waters of the flood. 8 Pairs of clean and unclean animals, of birds and of all creatures that move along the ground, 9 male and female, came to Noah and entered the ark, as God had commanded Noah. 10 And after the seven days the floodwaters came on the earth. Genesis 7:6-10
Discordance in molecular clock dating, which has wide extents, and the problems with other dating methods cause us to agree with Levinton’s dim view about those dating processes. All these things point to the young earth dating, and the accuracy and the power of Biblical records. 
The Lives during the Cambrian Period
The period, which the first life was created, is not confirmed, but it is estimated that the carbon, which is contained in a sedimentary rock found 38 million years ago in the west of Greenland, is originated from the organisms. In the west of Greenland, the well-preserved bacteria fossils are found, which came from 34.6 million years ago. In strata, which are a hundred million years old, probable fossils have been found.
Except for several arguable reports from Texas and India, the first multi-cellular organisms are considered to be created since 600 million years ago. From 600 million years to the beginning of the Cambrian Period, the organisms had flabby bodies, but quite various sorts of organisms have been found on all over the world. These organisms are called Ediacaran biota or Bendian biota. The organisms, which had hard shells, appeared at the last of this period.
Tons of various lives had been appearing since 544 million years ago.
At the very last of Precambrian Period, this period continued by appearing the various and modern Burgess biota fauna, which was started from the small shelly fauna. We call this change ‘Cambrian explosion’, which the biota became various rapidly.  
Precambrian is the unofficial name for the geographical features period, which is previous period of the Phanerozoic Eon. Precambrian Period began 450 million years ago, which is the period when the earth was formed, and until the Paleozoic era during the Cambrian period, which goes back to 54.2 million years.
Precambrian takes 7/8 of the history of the earth, but there are only few information of the Precambrian era. Also current information was revealed during the recent 40~50 years. According to the Zircon radiometric dating, which was found in the west of Australia, the earth’s stable crust was formed about 440 million years ago. The term ‘Precambrian’ is widely used for the geologists and paleontologists, but that term is not official name. The name should be classified as Proterozoic, Archaean, and Hadean.
Cambrian explosion is the geologic event, which various types of animal fossils suddenly appeared 542 million years ago. Moreover, from other crowding organisms, which use the phytoplankton or calcium, the diversity of similar forms was discovered. The lowest stratum in Cambrian,
The Importance of the Explosion
The explosion during the Cambrian aroused the interests of people and scientists. Charles Darwin thought creationists could use this phenomenon as major contrary reasons about evolution theory by their natural selections. Scientists have doubted that how this phenomenon had occurred so rapidly. The organisms, which are predecessors of the other organisms in Cambrian period, have not been found yet in the previous strata.
This phenomenon can be summarized as three followings:
- Did actually this explosion occurred?
- What stories can this phenomenon tell about the origin and evolution of animals?
- Why this phenomenon happened?
Around 19th century, geologists realized that the fossil records at the lowest stratum, which are now called the Cambrian stratum, increased suddenly. For Darwin, it was really serious problem that there are many animal fossils, but no their predecessor fossils, and actually he had spent lots of time to solve and explain this problem. Charles Walcott, who studied the animals in North America, proposed that during the “Lipalian” period, there were no fossils or not preserved, but faunas evolved in that period. However, the interests of this problems stirred by the book ‘Wonderful Life’, which is written by Harry B. Whittington’s and his researcher’s renewed explanation of the fauna in Burgess Shale, also by the aid of Stephen Jay Gould.
To estimate the period among different continents is such a hard work; it means to research ‘Cambrian Explosion’ is also a hard work. Most of Cambrian estimates were determined recently by the radiometric dating. Especially, there are spaces remain in the Paleozoic low stratum. The dating, which are utilized to important boundaries and the inheritable relationship among fauna, are not exact; should be read carefully until the better dating have made. 
Timeline Charts for Cambrian Period
|Neoproterozoic||Edicaran||545 - 600|
|Neoproterozoic III||600 - 650|
|Cryogenian||650 - 850|
|Tonian||850 - 1000|
|Mesoproterozoic||Stenian||1000 - 1200|
|Ectasian||1200 - 1400|
|Calymmian||1400 - 1600|
|Palaeoproterozoic||Stratherian||1600 - 1800|
|Orosirian||1800 - 2050|
|Rhyacian||2050 - 2300|
|Siderian||2300 - 2500|
|Neoarchaean||2500 - 2800|
|Mesoarchaean||2800 - 3200|
|Palaeoarchaean||3200 - 3600|
|Eoarchaean||3600 - 4600|
|“||the major bodyplans of animals all had to evolve very quickly, which is stretching the bounds of plausibility. - Shaun Doyle ||”|
|“||The possession of eyes (and probably nasal sacs) is consistent with Haikouichthys being a craniate, indicating that vertebrate evolution was well advanced by the Early Cambrian. Although evidently a jawless fish, its precise phylogenetic position is still speculative because this fish shows a puzzling mixture of characters contrary to some previous expectations. Kenneth R. Miller ||”|
|“||mussels, scallops and oysters' fossil shells are virtually identical to those of our present oceans. - Peter Ward ||”|
|“||The specimens may have been buried alive, possibly as a result of storminduced burial.’16 How about burial in a giant global Flood? - Paleontologists||”|
- George F. Howe and Carl R. Froede Jr. The Haymond Formation Boulder Beds, Marathon Basin, West Texas: Theories On Origins And Catastrophism Creation Research, CRSQ Volume 36(1) June 1999
- Speaking of Science Commentaries on recent news from science 500 Vertebrate Fish Found in Early Cambrian Creation Matters, Voulme 8, Number 1, January/February 2003
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- Michael J Oard Origin of vertebrates confirmed in the Early Cambrian Creation Ministries International (CMI) January 18, 2004
- Shaun Doyle Ediacaran ‘explosion’ Another thumping headache for evolutionists Creation Ministries International (CMI) March 5, 2008
- Anonymous Author Cambrian Period FlickrWorld November 27, 2008
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