Geology is the study of the physical processes of Earth from plate tectonics and volcanos to minerals and rock layers.  The field involves a combination of operational science and origins science.  The operational aspects involve measuring the types of rocks and minerals and where they occur, and current observable processes.  These things are all testable and repeatable in the present.  Geologists often attempt to reconstruct past events on the basis of their observations of present conditions.  It is in this area of origins science where creationists and evolutionist will often interpret the same evidence differently.

Geology is one of the most advanced disciplines of creation science.  There are at least two reasons for this.  First, the Bible gives some very specific details about the Earth’s geological past, including some specifics of the original creation of the planet, and also many details pertaining to the global flood.[1]  These historical facts have enabled creation scientists to develop detailed geological models.  We are able to explain things like plate tectonics, volcanos, the geologic column, and the ice age in light of the history recorded in Genesis.

A second reason is the publication of The Genesis Flood in 1961.  This book was written by the late Dr. Henry Morris and Dr. John Whitcomb.  Dr. Morris’s background in science specializing in hydrology made him an ideal researcher on the topic of flood geology.  Dr. Whitcomb’s education is in theology; his doctoral dissertation was on the Genesis flood, making him the perfect candidate to write on biblical issues.  In the 56 years since its publication, creation scientists have refined the geological models proposed by Morris and Whitcomb.  Nonetheless, to this day, The Genesis Flood remains a masterpiece of scientific and biblical research.

When it comes to the operational science aspects of geology, creationists and evolutionists are largely in agreement.  After all, the power of operational science lies in its testability.  Disagreements can be settled by performing an experiment.  And so we all agree on the composition of rocks, where they are found, and how they form today.  So it may be helpful to review some of the basics of operational geology.

Rocks and Minerals

Rocks are solid combinations of minerals.  A mineral is a naturally occurring, solid, (mostly) inorganic, chemical with an orderly crystalline structure.  Table salt is one example.  It is sodium chloride (NaCl), meaning it is made of sodium and chlorine ions in equal proportions held together by an ionic bond.  It has a crystalline structure that tends to form cubes.  Quartz is another example of a mineral.  A rock will contain several different minerals mixed together.

Rocks are classified into three primary categories based on how they form today.  Igneous rocks are those which formed at high temperature, having solidified from lava or magma as it cooled.  Volcanic rocks are igneous.  Igneous rocks can form underground as well.  Common examples of igneous rocks are basalt and granite.  Igneous rocks are those that are used in the process of radiometric dating.

Sedimentary rocks are those that were deposited by water or air.  At high speed, water can transport and deposit sediment such as sand.  If the sediment contains a cementing agent such as calcite, the grains can lock together, forming a rock.  Some examples of sedimentary rocks are sandstone, shale, and limestone.  Sedimentary rocks often contain fossils – the mineralized remains of organisms.

Metamorphic rocks are those which were once either sedimentary or igneous, but have been altered by heat and/or pressure.  Common examples are marble, slate, schist, and gneiss (pronounced “nice”).  Each has an original sedimentary or igneous progenitor.  Slate, for example, is produced when shale is metamorphized, whereas limestone can morph into marble.

The Geologic Column

In the origins debate, sedimentary rocks are especially important because they often contain fossils.  From these we can learn something about the organisms of the past.  Since the sediment was deposited by moving fluid, sedimentary rocks are often found in large horizontal layers, one on top of the next like a sequence of blankets.  These are strata.  Each layer seems to represent the material that was deposited continuously, with breaks in deposition separating layers.  In places where the rock layers have been vertically cut, such as in the Grand Canyon, it is very easy to see these horizontal layers and to distinguish one from the next by differences in color and texture.

Horizontal layering in the Grand Canyon

The horizontal layers are easily visible in the Grand Canyon

Geologists classify the fossil-bearing sedimentary rock layers into twelve major systems: Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian,[2] Permian, Triassic, Jurassic, Cretaceous, Tertiary, and Quaternary.  There is a statistical vertical order to these systems.  For example, if both Jurassic and Cretaceous rock layers are found in a particular area, the Cretaceous layer will generally be on top of the Jurassic.  Therefore, textbooks often depict these systems in a vertical sequence with Cambrian at the bottom and Quaternary on top.  This is called the geologic column.

Most places on earth do not contain the entire geologic column.  For example, you won’t find Jurassic or Cretaceous strata in Ohio.  But you will in Utah.  The geologic column is therefore a mental construct based on the observation that rock layers tend to occur in a particular order.  Secular geologists believe that these systems represent different periods of time in earth’s past, each representing many millions of years.  As such, they will often refer to things like the “Jurassic period.”  But in terms of observational data, the Jurassic is a lithographic system – a rock layer.

Systems are grouped into larger blocks called erathems.  The Cambrian through Permian systems belong to the Paleozoic erathem, Triassic through Cretaceous belong to the Mesozoic, and the Tertiary and Quaternary layers belong to the Cenozoic.  There are subdivisions of systems as well.  Most strata are continental in scale; they can be traced continually over most, but not necessarily all of a given continent.

Interestingly, fossils of some creatures are present in only some systems and absent in others.  Dinosaur fossils, for example, are found only in Mesozoic layers: the Triassic, Jurassic, and Cretaceous systems.  Trilobites are found in all the Paleozoic systems: Cambrian all the way through Permian.  But they are not found in any higher layers.  When a given organism is found in only one system, it is called an index fossil because it can then be used to identify that system if found in other regions.  The lower systems contain only fossils of marine organisms, but the higher layers contain a mix of both marine and terrestrial organisms.  Fossils below the Cambrian system are rare, and are primarily microbes.

Whereas secular geologists interpret the fossil-bearing strata as representing vast ages, creation scientists interpret most of them as progressive stages of the global flood.  The Cambrian system seems to represent the initial stages of the flood.  Systems below the Cambrian are thought to be pre-flood layers that were likely formed when God created the Earth and separated the land from the water.  There is some debate as to which layer represents the last stages of the flood, but nearly all agree that it extends at least through the Cretaceous, and perhaps well into the Tertiary.   The upper Tertiary and Quaternary systems are thought to be post-flood.

Plate Tectonics

In 1858, Antonio Snider-Pellegrini proposed that the continents were not always separated as they are today.  He argued on the basis of fossil evidence that they were originally connected into a supercontinent, and were pushed apart during the global flood.  The fossil and lithographic evidence for this is quite compelling.  For example, fossils on the east coast of South America match those on the west coast of South Africa.  Furthermore, the shape of the continents is such that they do fit together, like separate pieces of a jigsaw puzzle.  When connected, the rock layers and fossils match nicely.  Creation scientists today largely agree that Snider-Pellegrini was right.

However, most geologists at the time dismissed the idea.  The notion that something as large as a continent could move may have been difficult to accept.  And the mechanism was unknown at the time.  Later research supported the notion of plate tectonics: that earth’s crust is divided into a number of movable plates that essentially float on earth’s mantle.  The boundaries between plates are marked by regions of volcanos and earthquakes, sometimes called the Ring of Fire.  Collision between plates can cause mountain chains.  Plate tectonics provides a credible mechanism for the separation of the continents and the formation of mountain ranges that occurred during the global flood.

But the theory of plate tectonics and continental drift did not catch on until the late 1960s.  And secular geologists had to modify the idea to accommodate their belief in vast ages.  Rather than breaking up at the time of the global flood, they proposed that the plates gradually drifted apart over millions of years.  So creation geologists and secular geologists largely agree on the mechanism of plate tectonics, continental drift, mountain building, and volcanos.  They simply disagree on when these events occurred and how quickly they took place.

Interpreting the Data

When attempting to reconstruct past events, scientists inevitably rely upon certain presuppositions to help them make sense of the data.  We all agree on data.  We agree that fossils are found in sedimentary rock layers, that these layers are deposited on continental scales, and that there is an order to the rock layers.  We agree that the Earth was quite different in the past, and that fossils and rock layers reveal this information.  But our presuppositions differ.  And so we draw different conclusions regarding how and when these past events took place.

The secular view is driven by the philosophy of uniformitarianism.  The belief is that present rates and processes are largely the same as past rates and processes.  The uniformitarian motto is “the present is the key to the past.”  Secular geologists assume that the rate at which mountains were pushed up in the past is similar to the miniscule rate at which they are being pushed up today, and that canyons have always eroded at about the same small rate they are being eroded today.  They assume that since the continents are moving only very slowly today, that this was always the case.  If these assumptions are true, then it must have taken millions of years for mountains to form, for canyons to form, and for the continents to have drifted at their current slow rate to their present positions after splitting apart from the original supercontinent.

On the other hand, creation scientists reject the belief in uniformitarianism and instead believe that most of Earth’s geological features were produced rapidly, during the creation week and during the global flood.  During these events, the rate at which sediment was deposited, and the rates of mountain-building and canyon formation would have been immensely greater than the rates today.  Under such catastrophic conditions, there is no need for millions of years.  Any residual continental drift, mountain building, and canyon erosion that takes place today would be infinitesimal compared to the rates that took place during the flood year.  Therefore, we may not blindly extrapolate from present rates conditions to past rates and conditions.  For biblical creationists, the Bible is the key to the past, the present, and the future.

Most people have been taught the secular interpretation of the data, and are unaware of the biblical creation interpretation.  But the data are exactly the same.  It is not as though creationists have one set of fossils and secularists have a different set.  We are all looking at the same rock layers, fossils, canyons, and mountain ranges.  But our differing philosophical interpretive frameworks drive us to draw very different conclusions from the same data.  Can we rationally determine which view is the correct one?  Are the geological data equally compatible within both frameworks?  If so, is there some other way to determine which view of origins is the correct view?  In our next article we will answer these questions.


[1] In contrast, consider the historical details the Bible provides regarding the origin of the celestial bodies beyond the solar system: “He made the stars also.”  (Genesis 1:16)

[2] Outside of North America, the Mississippian and Pennsylvanian are often treated as one combined system called the Carboniferous.