Multiple and integrated evidences of geology regarding the age and prehistory of Earth

by Christadelphian geologist Roger Evans

There are three basic types of rock.

• Sedimentary rocks are those deposited, generally in layers, from a transporting medium (water or air), by physical means (gravitational or tractional settling), or by chemical means (precipitation from solution).
• Igneous rocks are those formed by cooling from a molten state; whether erupted on to the surface (volcanic) or intruded beneath the surface (plutonic).
• Metamorphic rocks are those altered in situ from their original form by heat and pressure, with attendant partial or total recrystallization.

Spatial relationships between bodies of rock (founded upon basic laws of physics) together with their physical and chemical characteristics, and the biological relics they contain, form the fundamental framework of geology.

Lithostratigraphy

Nicolas Steno, in 1669, formulated four basic laws, or principles, regarding stratified rocks:

The Principle of Superposition: In a sequence of strata, any stratum is younger than the stratum on which it rests, and older than the stratum that rests upon it.

The Principle of Original Horizontality: sediments are initially laid down in horizontal layers, with any tilting being subsequent to deposition.

The Principle of Lateral continuity: that these horizontal layers are laterally continuous until a constraining impediment is reached.

The Principle of cross cutting relationships: That if a feature (such as a fault, or an igneous intrusion) cuts across these layers, then that feature must post-date the strata.

Biostratigraphy: macropalaeontology

William Smith, studying layered rocks in England during canal construction in the early 19^th century, noticed that each layer was characterised by a particular set of fossils. This led to the formulation of a fifth principle, The Principle of Faunal Succession: that successive strata contain unique fossils that correspond with their relative age.

As the principle of faunal succession was applied round the world, it was noted that though the type of rock varied, the succession of particular “marker” fossils was always relatively the same (this is because strata are determined by the type of sediment locally available at the time, but fossils are potentially more cosmopolitan in their distribution).

The various marker fossils are not mixed up, as one might expect if all lived contemporaneously, but consistently succeed each other in an ordered succession. This indicates a change in biota with time; with extinction of older forms, and the appearance of new forms in their place.

There has clearly been dramatic change and succession in forms of life on earth over time.

The principles of succession of layers, combined with the principle of succession of biota, have enabled reconstruction of the stratigraphic column.

It is often argued that the column is a fiction because the complete sequence is found nowhere on earth. This is a fallacy. Using the principles of succession, reconstruction of the column is as easy as ABC. For example:

At Location 1, there is a sequence of strata: A,E,F,G,H, K

At location 2, there is a sequence of strata: A,B, C,D,E,F,L,M

At Location 3, there is a sequence of strata: F, G, H, I ,J,K,L.

Though some letters are missing, the letters are in correct relative alphabetic order. By correlating identical letters, which represent successive strata containing marker fossils, we can reconstruct the full original sequence.

Breaks in the sequence almost always correspond with recognisable breaks in deposition (such as erosional or angular discordances, or unconformities), giving an extra clue to the elision at each location.

The collective and systematic evidence is that the earth has undergone a prolonged period of development, with particular life forms succeeding each other over time.

Biostratigraphy: Micropalaeontology

In the later 19^th century, largely in response to a need to identify strata from borehole cuttings in the growing petroleum industry, attention focused on tiny fossils, pinhead or smaller in size (pollen, shells of plankton), collectively known as microfossils.

Continuing study established that there was a distinct succession of microscopic marker fossils with time, and that these also formed a biostratigraphic sequence, completely in agreement with the sequence determined by macropalaeontology.

Various forms of plankton (foraminifera, coccoliths, radiolaria, diatoms) and pollen, can be used in biostratigraphy, and are invaluable owing to their wide distribution and their presence in most rocks, particularly those containing no macrofauna.

Lithostratigraphy, macropalaeontology and micropalaeontology together consistently establish the relative, A-Z, succession of strata observed on earth.

Chronostratigraphy

By the twentieth century, although the relative age of the strata had been established, the actual age, in terms of time, remained unknown. However, with the discovery of nuclear physics, particularly the principle of isotopes and their stability/ decay, this was about to change.

Physics has established (by repeated experiment) that radioactive isotopes of certain elements decay with time, at measurable average rates, into derivative isotopes. For each particular parent‑to‑daughter reaction, this rate is constant over time.

The principle that follows is: that by establishing the ratio of parent to daughter isotopes in an igneous rock, the amount of time that has expired since that rock was formed can be deduced.

There are various methods, suited to different rock types of different ages. Often these methods can be used to cross check each other.

Igneous rocks (or volcanic ash) interlayered with sedimentary rocks can therefore be used to calibrate the age of the sedimentary rocks, and of the fossils they contain.

The overall consensus of radiometric dating enables the assignment of “absolute” ages to the stratigraphic column, and confirms that the relative A-Z order established by lithostratigraphy, macropalaeontology and micropalaeontology is correct. By providing absolute (time) ages, it proves that the earth is millions of years old.

Suggestions that the rate of decay may have changed with time are speculative, entirely without physical proof, and would require a change in the laws of physics. Thus radiometric dating, on the grounds that God’s laws have remained constant from creation, confirms an old age for the earth.

Plate Tectonics

Prior to the 1950s, disruption of strata by tectonism (earth movement) was widely observed, but difficult to explain. Folding, and overthrusting, of strata require lateral shortening, but no mechanism was known. The earth’s crust was considered to be universally solid and immobile.

Alfred Wegener observed that the coastlines of some continents apparently matched as if they had once fitted together, and that the strata on each continent across this apparent line of fit were of the same lithology and age, with identical fossils. He postulated that these continents had once been joined as a single entity, and that they had moved apart. However, his idea was ridiculed, as the idea of continents migrating through or over solid oceanic crust was physically inconceivable.

However, increasing and new research subsequently found (using the Atlantic Ocean as an example):

• That the basalt sea floor to either side of the ridge shows zones of magnetic reversal, which run parallel to the mid-ocean ridge and to the continental coasts.
• that there is a raised ridge running down the middle of the ocean. This comes to surface on land in Iceland, where the land is observed to be continually splitting apart with rifting and volcanism. The ridge is slowly spreading apart.
• bedrock samples obtained by deep sea drilling, dated by radiometric methods, show that the basalt sea floor is progressively older in age with distance away from the ridge.
• deep sea drilling also shows, from microfaunal ages, that the sediment cover is not uniform across the ocean, but gets thicker with increasing distance away from the ridge, and that the sediments at the base of the sequence are progressively older.

The physical corollary of spreading, crustal shortening, is found in the presence elsewhere of collision zones, where land is being forced together, and/or consumed in subduction zones. Here is the missing mechanism that explains folding and overthrusting.

The rate of spreading can actually be measured, by surveying techniques, measuring the rate of increasing distance between fixed points on either continent. It has been established that the Atlantic Ocean has an average rate of spreading of 2.5cm/year. The Atlantic Ocean has an average width, perpendicular to the spreading ridge, of 3000km. The oldest ocean floor sediments on each side of the ridge are of Late Jurassic to Cretaceous age (about 200-100 million years old). Rocks older than this, on the two continents, can be geologically matched, like joining two separated pieces in a jigsaw.

Assuming a consistent rate of spreading, a simple back-calculation of rate and distance from the present day confirms the age of the Atlantic Ocean.

Speculation that the rate of spreading may have been much greater in the past is unfounded, would require catastrophic variation in the physical laws and processes governing our planet, and contravenes the physical proofs of radiometric dating. Plate tectonics confirms a measurable and calculable ancient age for earth, and for the existence of life upon it.

Palaeoecology and palaeoenvironment

In the modern world, ecology is the study of organisms in their relationship to each other and to their environment, as a collective whole. Palaeoecology is the study of fossils within a stratum relative to each other and relative to the stratum in which they are found. Palaeoenvironment is determined by the characteristics of the sediments, compared to those in present day environments.

In the modern environment, peat swamps consist of vegetation that grows and accumulates in situ. It can contain stumps and roots in growth position, and does not contain marine shells. In the ancient environment, we recognise these as coal measures.

In the modern tropical environment, reef forming corals need light and clear water to grow, and they cumulatively build large continuous reefs in situ. Where we find coral reefs among ancient strata, we can reasonably infer that they grew in situ in a sediment-free environment of shallow, sunlit water.

Particular assemblages of organisms live interdependently in particular environments—and similar assemblages are found in geological strata, enabling reconstruction of the ancient ecology. Animals leave footprints in mud on land, and sea creatures leave trails and burrows in sea floor sediment. When these assemblages, and physical traces and trails, are observed in geology, they indicate that the organisms were actively living in the sediment, in particular environments, at the time at each particular stratum formed.

Such evidence indicates that the strata of the earth formed progressively, in a wide range of ancient environments, over time, and that the particular organisms present were, in many cases, actively living and dying in or on the sediments during their deposition.

The concept of a single global catastrophic inundation to account for all fossiliferous strata is completely contrary to the physical evidence preserved in the geological record.

Geological continuity

It is postulated by some that there is a “gap” between the older geology of the earth and the present creation upon it. However there is no proof in the geological record of such a break. Rather there are evidences of continuity:

• the long term occupation of different continents by diverse kinds of animals—for example Australia’s unique fauna—rather than global uniformity of distribution;
• the longevity and preponderance of terrestrial weathering and deposition in larger continents such as Australia, with no evidence of global marine inundation;
• the longevity of glacial ice in the polar regions (particularly Greenland and Antarctica), where analysis and dating of ice cores indicates at least 0.8 million years of ice accumulation (a global inundation would have floated and dispersed any pre-existing ice).

Theory, in the scientific sense, is a best-fit explanation developed from analysis of all of the known facts. Gap theory is not really a theory, but a speculative hypothesis that attempts to conform facts to an existing preconception.

Summary

The consensus of extensive research in the scientific discipline of geology, confirmed by multiple techniques developed over time, harmonious through all subdisciplines, and consistent with other major scientific disciplines, is this:

That the Earth, and life upon it, is of considerable age, and has undergone a continuous process of change and development over many millions of years; and that these processes continue unbroken into the present.

This brief and very generalised outline is by no means a detailed or precise account of the proofs of geology, but is a basic outline of the factual consensus; and a challenge to all who doubt these things, to assess the evidence for themselves.

There are two means of assessing evidence, ably summarised in Acts 17:11:

The Thessalonian Method — putting preconceptions first and selecting, modifying or rejecting the facts to suit;

The Berean Method — assessing the facts first, and confirming, modifying or rejecting one’s conclusions accordingly.

Which method is most likely to discover truth? Which method do we use in comprehending Scripture, and which method do we use in understanding Science? And are we consistent?

One final thought

We expect anyone coming to Scripture to approach it with a willing and teachable heart. We know immediately that anyone approaching with hostile preconception, looking only for contradictions to confirm their scepticism, is doomed to miss the message.

The same applies to our approach to science. If we really want to understand God’s Creation, and to judge His works honestly and truthfully, we must undertake careful, prayerful reading and research, with an open and receptive mind.

This should be done before speaking authoritatively in the name of, and on behalf of, our Creator, regarding what He has made and done.

— Roger Evans (M.Sc, Geology)
September 2013

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