Samuel Clifford

 

1/12/2026

 

This article was made from my notes on the textbook that is cited below as I took a Physical Geology introductory class. I tried to add my own notes and examples to what the textbook states. As this is not a full read through for the course, some sections will not have notes. 

 

Tarbuck, Edward J., Frederick K. Lutgens, and R. Linneman. *Earth: An Introduction to Physical Geology*. 13th ed., Pearson, 2019.

 

Chapter 1: An Introduction to Geology (Sections 1.3, 1.4, 1.6, and 1.7)

 

1.3

 

The textbook defines science as “a process of producing knowledge” (Tarbuck, Lutgens, and Linneman 11). This process relies on closely observing what happens and developing explanations that account for those observations.

 

“All science is based on the assumption that the natural world behaves in a consistent and predictable manner that is comprehensible through careful, systematic study.” (Tarbuck, Lutgens, and Linneman 11). This statement is a uniformitarian concept that is distinct from catastrophism and creationism which teach that the Earth’s features formed mainly through violent and sudden events.

 

Hypothesis- “a proposed explanation for certain phenomenon that occurs in the natural world” (Tarbuck, Lutgens, and Linneman 11). A hypothesis can only become an accepted part of scientific knowledge after it has passed testing and analysis and therefore a hypothesis must be testable and it must be able to make predictions based on the hypothesis being considered.

 

At this point, creationists usually state the difference between Operational Science and Historical Science. Operational Science absolutely depends on testable, repeatable hypotheses, and creationists agree with that. But when the discussion is on origins—events that happened once in the distant past— then the hypothesis and experiment shift from Operational Science to Historical Science. In historical science, neither creation nor evolution can be directly repeated or observed, so both sides rely on interpretations of present‑day evidence.

 

Theory- “a well tested and widely accepted view that explains certain observable facts” (Tarbuck, Lutgens, and Linneman 11). 

 

At this point I’d like to give some of my own thoughts specifically on the Theory of Evolution and Abiogenesis. There are many examples and data I can give that contradicts the Theory of Evolution and Abiogenesis in how it is believed today. Creationists believe in speciation but not the idea that all life formed from a common ancestor. The problem with the Theory of Evolution compared to other theories is that: 

 

1. A theory is an explanatory framework built from interpreting present‑day evidence, but when it deals with past, unrepeatable events—such as origins—it is not “proven” in the same way as operational scientific theories. Instead, it is a model that organizes data according to a set of starting assumptions (worldview), and its predictions must be evaluated against observable limits in biology, geology, and genetics.

 

2. Specifics of evolution change frequently due to new data being collected. Data can vastly change interpretations especially when data is either left out or added. The Theory of Evolution cannot have repeatable testing in the sense of proving the entire scale of evolution in its modern use, and it seems that when all data is considered, creationists can actually account for more than uniformitarian view points. This will be discussed much more in future articles. 

 

1.4

 

The Earth has four main spheres; the hydrosphere (the water portion of our planet), the atmosphere (the gaseous layer of Earth), the biosphere (all life on Earth), and the geosphere (solid Earth). Each is related to others in ways and interact continually.

 

Earth System Science- “an interdisciplinary study that seeks to examine Earth as a system composed of numerous interacting parts or subsystems” (Tarbuck, Lutgens, and Linneman 15)

 

1.6

 

Crust:

 

The Earth’s crust is relatively thin compared to other layers. It consists of continental crust and oceanic crust. Oceanic crust is roughly 4.5 miles thick and composed of basalt. The continental crust averages at 22 miles but is known to exceed 45 miles in some mountainous regions.

 

Mantle:

 

The Earth’s mantle makes up more than 82 percent of the Earth’s volume. It extends to a depth of about 1800 miles. The dominant rock type in the upper mantle is peridotite. The upper mantle can be split into three parts:

 

1. Lithosphere: consists of the entire crust plus the uppermost mantle. 

 

2. Athenosphere: a soft, comparatively weaker layer. The lithosphere is able to move independently of the athenosphere.

 

3. Transition Zone: identified by a sudden change in density from 3.5 to 3.7 g/cm^3.

 

The lower mantle ends at the top of the core and strengthens with more depth due to the increased pressure. 

 

Core: 

 

The core is at the center of the earth and is composed of iron and nickel alloy mostly. The core is composed of two different layers, the outer core which is the liquid layer, and the inner core which is solid due to the immense pressure it is under. 

 

1.7

 

Geologists separate rocks into three major groups: igneous, sedimentary, and metamorphic. 

 

Rock Cycle- “a model that illustrates the origin of the three basic rock types and the interrelatedness of Earth materials and processes” (Tarbuck, Lutgens, and Linneman 24).

 

Magma is molten rock that is underground and then goes through crystallization where it solidifies to form igneous rock. Igneous rock at the surface goes under weathering in which other conditions disintegrate and decompose rocks and forms sediment. Sediment then goes through lithification in which sediment becomes sedimentary rock when it is compacted or cemented. Sedimentary rock, and Igneous rock that was not weathered, then can be buried deep within the earth and go under immense heat and pressure. This changes the rocks and they become metamorphic rock. Metamorphic rock can then be heated too much and return to a magma form and thus continue the rock cycle.

 

Chapter 9: Geologic Time (Sections 9.1, 9.3, and 9.4)

 

9.1

 

Principle of Superposition- a principle that states that every sedimentary layer in a rock bed is older than the rock layer above it. 

 

Principle of Original Horizontality- states that layers of sediment are generally deposited in a horizontal position. 

 

Principle of Lateral Continuity- states that all sedimentary beds originate as continuous layers that extend in all directions until they thin out or the sediment changes.

 

Principle of Cross-Cutting Relationships- states that geological features that have cut across rock must form after the rocks they cut through.

 

Principle of Inclusions- the rock mass adjacent to the one containing inclusions must have been there first in order to provide the rock fragments.

 

Unconformities:

 

When layers of rock are deposited without interruption, they are called conformable. However, there are many unconformities in the rock layers in which a long period of deposition ceased or erosion erased previously formed rock and then deposition continued, leaving behind a gap in time. 

 

Angular Unconformity- an unconformity in which the older strata dip at an angle different from that of the younger beds.

 

Disconformity- a gap in the rock record that represents a period of erosion and not deposition. 

 

Nonconformity- younger sedimentary strata overlie older metamorphic or igenous rock.

 

9.3

 

Correlation- the method geologists use to match rock layers of the same age across different locations.

 

English engineer and canal builder William Smith formulated the Principle of Fossil Succession. It states that fossil organisms succeed one another in a determinable and definite order and that geological time periods can be identified by its fossil content.

 

Index Fossils- fossils that are associated with a specific geological time period. 

 

9.4

 

Radiometric dating is based on the behavior of atoms, which are made of protons and neutrons in a central nucleus surrounded by electrons. Some atoms have unstable nuclei, meaning they have too many or too few neutrons to remain stable. These unstable atoms undergo nuclear decay, a natural process where the nucleus spontaneously changes into a more stable form by releasing particles or energy. As an unstable “parent” atom decays, it transforms into a stable “daughter” atom at a predictable rate, allowing scientists to measure how much decay has occurred.

 

By comparing the amount of parent isotope remaining to the amount of daughter isotope produced, scientists can calculate how long the decay has been happening. This makes it possible to determine the absolute age of rocks, fossils, and other materials. Different isotopes are used for different time ranges—carbon‑14 for recent organic remains, and methods like potassium‑argon or uranium‑lead for much older geological materials.

 

Refer to my article on the assumptions of radiometric dating to understand it from a Young Earth Creationist perspective:

 

https://www.samtheology.com/articles/science/radiometric-dating-and-the-hourglass-analogy