Dr. Jason Lisle: Creation 101: Geology Part 1 (original source here)
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. 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. Continue reading