Stories in the Strata

Lyell made his case for an ancient Earth based on geological observations, envisioning an interpretation of the data that would defy the claims of Genesis. Even now, most that stand in defense of deep-time stand on those same geological observations and others, including new insights taken from biology, archaeology, and cosmology. What of their claims? Upon what evidences do they stake their defense of an old Earth, indeed an old universe, and what investigatory methods led them to that position?

For geology, it typically comes down to the strata – or layers – of rock which allows researchers to make their case. Strata are formed, according to the authorities in the field, by a gradual process which depending on various conditions may take many thousands of years, or longer, to form. For sedimentary rock, the oldest are typically found the deepest, with newer rock forming closer to the surface. That formation is interesting in its own right, with the process starting with established rock that has been subjected to the weathering effects of wind, rain, and ice, in effect forming smaller fragments or sediments. These sediments, carried by the same wind or water that contributed to their formation, come to rest in other areas with the heaviest material settling first and the lightest material settling further away from the point of origin in a process known as deposition. Together the weathering and deposition of sediments is known as erosion. 

After the sediments have been deposited two things begin to take place. The first – compaction – occurs as sediments accumulate, growing in weight, and pressing down with ever more force on those sedimentary layers beneath it. As the compression continues, the pressure becomes so great that whatever water may yet remain between the particles of sediment is eventually pushed out! During this comes the process of cementation, whereby minerals that had dissolved in that water accumulate between the individual sedimentary fragments, eventually hardening and fusing them together. 

The entire process, from individual sediments to finalized sedimentary rock strata is known as lithification, and according to the geological authorities, takes perhaps millions of years to see completion. As such, standing before a great cliff face rising several hundred feet in the air, untold layers of strata shining forth in multicolored bands that each took several millennia to form, it is no doubt how Lyell and those like him would conclude that the Earth is of an ancient age. 

The practice of studying the strata and the fossils they contained was the primary method for determining the age of any given site during the late 18th and early 19th centuries, and still the method is used to provide insights into relative dating. Through relative dating, researchers attempt to formulate a chronological image through the strata, understanding which layers are older or younger, how that corresponds to the fossils found therein, and generally attempting to make sense of all the information available.

To determine the relative age of a series of strata, researchers use several methods of analysis. Primarily, they rely on the concept of superposition, whereby, quite logically, the oldest rock beds are expected to be found beneath newer ones. The whole concept relies on two simple assumptions: 

  • That the strata were formed in a nearly horizontal position, and…
  • That those beds were not disturbed or overturned at some point following that deposition. 

Next, researchers examine the strata for faunal succession, whereby the various layers are expected to demonstrate distinctive fossils which are to occur, based on the evolution paradigm, in a characteristic order. Like the concept of superposition, researchers use occurrences of faunal succession to establish the relative ages of specific strata. Often times, certain widespread fossil forms are utilized to reference ages across various regions – or even globally – based on their occurrence within specific strata. These are referred to as index fossils, with the process as a whole being known as biostratigraphy. As such, researchers who recognize a particular fossilized shellfish in North American rocks and likewise in Australian rocks will often conclude that the strata in which both sets of fossils were discovered must represent a common age. Interestingly, the inverse of the scenario is also utilized, whereby the strata in which the fossils are found provide an understood age for the fossils found therein…

Other methods that researchers rely on to determine relative ages of strata involves analyses of crosscutting and inclusions, whereby examples of volcanic or other geological activities which have disturbed a stratum (crosscutting) or alternatively instances of larger, older rock fragments found within newer layers (intrusion) are noted and used to assist in establishing the relative age of series of strata.

4.01 Geological Block Model of Superposition, Crosscutting, & Intrusion.jpg
Geological Model of Superposition, Crosscutting, & Intrusion

While relative dating provides insights into the general chronological sequencing of a geological series, it cannot provide any conclusive data concerning the actual age of the rocks in question. For that researchers utilize other methods to conclude the absolute age of the strata and the fossils they contain, most notable among these being nuclear decay. 

As radioactive isotopes decay, their inherent chemical signatures change, with a parent isotope changing into a daughter isotope over time. Assuming such decay occurs at a constant rate, researchers analyze these isotopes in an effort to establish an approximate absolute age, relying on the half-life  – or the time it takes for half of a parent isotope to become a stable daughter isotope – of the isotope to confirm their conclusions.

More specifically, mainstream researchers assert that a number of minerals contain concentrations of natural radioactive isotopes, many of which possessing extremely long half-lives that are believed to be unaffected by any conditions that occur after these minerals become rocks. Thus, by examining the ratios of parent and daughter isotopes within these rocks, researchers establish the absolute age (otherwise known as the radiometric age) of them, and by association, any fossils found within them. 

Chemically, the most viable materials for such radiometric dating are igneous rocks, with metamorphic rocks typically yielding results that only establish the age at which its metamorphosis occurred. Sedimentary rocks, especially those assumed to be ancient in their origins, are ill-suited for radiometric dating. Conversely, such rocks less than 60,000 years in age possessing organic material can be dated using the isotope carbon-14, which allegedly possesses a half-life of 5730 years. Most people with at least a basic knowledge of radiometric analysis are familiar with this process, known as carbon dating, and by and large, it is the ‘go to’ metric for those establishing the dates of recent fossils and artifacts.

4.02 Model Demonstrating Radioactive Decay in Carbon-14
Model Demonstrating Radioactive Decay in Carbon-14

With the two processes together, relative dating through physical examinations of geological material and absolute dating of the chemical components of that material, geologists and other researchers confidently assert the age of the Earth and the fossils found throughout her sediments. Despite the authority with which they declare their findings, the processes they use are not in fact as definitive as they would have you believe…

– This was an excerpt fromRemnants of Eden: Evolution, Deep-Time, & the Antediluvian World.” Get your copy here today. God bless! –

 


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