The geologic
time scale is a system of
chronological dating that relates geological
strata (stratigraphy) to time. It is used by geologists, paleontologists, and other Earth scientists to
describe the timing and relationships of events that have occurred during
Earth's history
The use of radiometric dating is also applied to the layers of the geologic record to establish the absolute ages of the layers and the billions of years indicated by the rock layers. In order for life to have evolved, the earth must be extremely old, so the assumption of long ages is applied to the geologic record to support the evolutionary philosophy.
The ten or eleven strata systems that geologists use (Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, and Tertiary) compose the "standard geologic column" and are claimed by many to contain the major proof of evolutionary theory.
From the biblical creationist perspective, however, there are several events that must be considered when interpreting the evidence of the earth’s history recorded in the rocks. Just as evolutionists assume that the earth began as a random, molten mass, biblical creationists assume that the earth began with supernatural acts of God—forming the original rocks and layers. These layers and rocks were then catastrophically rearranged and redeposited during the Genesis Flood. As the waters covered the earth, and later flowed off the continents as the mountains rose, the major erosional features, like Grand Canyon and Uluru, were carved out. Modern examples of canyon formation and rapid erosion provide models to explain how many formations can be described by the Flood and its aftereffects—and all within a few thousand years.
When layers
of earth are exposed, a little digging can often unearth some type of ancient
fossil, which scientists then determine their age by what level they were found
Several erroneous notions have been attached to the geologic column—below are the ten most common misconceptions.
• Misconception No. 1. The geologic column was constructed by geologists who, because of the weight of the evidence that they had found, were convinced of the truth of uniformitarian theory and organic evolution.
It may sound surprising, but the standard geologic column was devised before 1860 by catastrophists who were creationists. Adam Sedgewick, Roderick Murchison, William Coneybeare, and others affirmed that the earth was formed largely by catastrophic processes, and that the earth and life were created. These men stood for careful empirical science and were not compelled to believe evolutionary speculation or side with uniformitarian theory. Although most would be called "progressive creationists" in today's terminology, they would not be pleased to see all the evolutionary baggage that has been loaded onto their classification of strata.
• Misconception No. 2. Geologists composed the geologic column by assembling the "periods" and "eras" which they had recognized.
The geologic column was not composed by assembling a chronology of "periods," "eras" or other supposed measures of time, but by periods" and "eras" were later appended to the system nomenclature of the "geologic Column" transforming it into a "geologic time scale."
• Misconception No. 3. The strata systems of the geologic column are worldwide in their occurrence with each strata system being present below any point on the earth's surface.
The notion that the earth's crust has an "onion skin" structure with successive layers containing all strata systems distributed on a global scale is not according to the facts. Data from continents and ocean basins show that the ten or eleven systems are poorly represented on a global scale: approximately 77% of the earth's surface area on land and under the sea has seven or more (70% or more) of the strata systems missing beneath; 94% of the earth's surface has three or more systems missing beneath; and an estimated 99.6% has at least one missing system. Only a few locations on earth (about 0.4% of its area) have been described with the succession of the ten systems beneath (west Nepal, west Bolivia, and central Poland). Even where the all the systems may be present, geologists recognize individual systems to be incomplete. The entire geologic column, composed of complete strata systems, exists only in the diagrams drawn by geologists!
• Misconception No. 4. Strata systems always occur in the order required by the geologic column.
Hundreds of locations are known where the order of the systems identified by geologists does not match the order of the geologic column. Strata systems are believed in some places to be inverted, repeated, or inserted where they do not belong. Overturning, overthrust faulting, or landsliding are frequently maintained as disrupting the order. In some locations such structural changes can be supported by physical evidence while elsewhere physical evidence of the disruption may be lacking and special pleading may be required using fossils or radiometric dating.
In fact, if you look at an individual rocky outcrop, it is certainly usually the case that the higher-up rock is likely to be younger than the lower rock. However, this says nothing about the supposed timescale of the geologic column. For example, it is quite common to find fault lines where lots of layers of rock are bent and curved together. Yet these layers supposedly represent millions of years. But, in order for the folding and curving to occur across these layers, they must all have been still plastic when the folding occurred. Therefore, they cannot be millions of years old, and the age difference between higher and lower rocks in these structures can only be days, rather than millions of years.
• Misconception No. 5. Because each strata system has distinctive lithologic composition, a newly discovered stratum can be assigned easily to its correct position in the geologic column.
Sandstone, limestone, dolomite, shale, chert, salt, conglomerate, coal and other rock types are not diagnostic of specific strata systems. Therefore, a rock's physical appearance cannot, with certainty, distinguish the system or strata level to which a rock may belong. The sequence of rock types is more useful, but hardly an infallible guide to correlation. Thus, the Cambrian System on an intercontinental scale is typically composed of quartzose sandstone, overlain by glauconitic sandstone with dark-brown shale, overlain by impure, light-brown limestones. The correlation of "Cambrian" strata is further strengthened by the presence on an intercontinental scale of an unconformity (surface of erosion) at or near the base of the system. Each rock type is not distinctive of the Cambrian, and neither is the unconformity, but the sequence may be.
• Misconception No. 6. Fossils, especially the species distinctive of specific systems, provide the most reliable method of assigning strata to their level in the geologic column.
Bed-to-bed correlation of strata to their "type system" area is the most reliable method of assigning strata to a system. The data from oil well drilling, seismic surveys, and surface geologic mapping is of such character that subsurface correlation of lithostratigraphic units of the thickness of systems is possible on a continental scale. Although some fossils appear to be distinctive of certain systems (most fossil taxa range through a few to several systems), care must be exercised in correlation by fossils.
First, the stratigraphic range of a fossil type is always open to extension as new fossils are discovered. Second, when an extension of a fossil's range may be required, geologists may call upon erosion (reworking fossils into younger strata or leaking fossils into older strata) and structural events (overturning or faulting strata and fossils). An example of the first problem is the monoplacophoran mollusk Pilina, which might otherwise be considered diagnostic of the Silurian System, except for the startling discovery that Neopilina lives today, and, therefore, would be expected in any system overlying the Silurian. For these reasons correlation by fossils must always remain tentative awaiting further confirmatory evidence from lithostratigraphy. We should look very skeptically at strata correlations which rely solely on fossils.
(See the next post, “Misconceptions about the Geologic Column – Part II,” for more on how people misunderstand the geologic column and geology in general and its impact on the believability of the young Earth age of 13,000 years)
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