Geology Fundamentals

Understanding Science

• Geology is the science of the Earth.
• It studies Earth's composition, structure, origin, life forms, physical and chemical processes, and history.
• Geology is an interdisciplinary science involving physics, chemistry, biology, mathematics, astronomy, and other sciences.
• Geology is considered unique because it involves the element of time, specifically 4.5 billion years of history.

Applications of Geology

• Helps locate, extract, and manage natural resources.
• Used to evaluate the environmental impacts of using or extracting resources.
• Controls the distribution of resources based on age, rock type, and regional geologic history.
• Deals with mineral resources like iron, copper, and salt.
• Used to estimate and mitigate hazards and risks.
• Helps estimate the likelihood of future events and understand past events.
• Influences our lives through natural hazards like hurricanes, flooding, earthquakes, volcanoes, and landslides.
• Geologic hazards occur in specific locations for specific reasons.
• Explains Earth's features, such as the landscape features of North America, including mountain ranges and valleys.
• Provides insights into volcano distribution and continental positions.
• Gives evidence of ancient life and past global climate change.

Geologists and Their Role

• A geologist is a scientist who studies the Earth's structure, composition, and history.
• Geologists play a crucial role in understanding the planet and its resources.
• Geologists engage in fieldwork and mapping, lab work, computer work, and report writing.
• The study natural hazards to understand the risks to communities as well as Earth's resources for economic developments.
• Also study rocks, fossils, and structures to understand processes that have shaped the planet.
• Different types of geologists include geochemists, volcanologists, environmental geologists, and geobiologists.

The Scientific Method

• The scientific method involves systematic observations, measurements, experiments, and the formulation, testing, and modification of hypotheses.
• The steps include making an observation, identifying a problem, forming a hypothesis, conducting an experiment, peer review, and scientific theory development.
• Scientific theory development involves a hypothesis that has been repeatedly tested for falsifiability through documented and independent studies.
• The scientific method is continuous and self-correcting.

Observations vs. Interpretations

• Observation is a comment or statement about what is seen or perceived.
• Interpretations are logical scientific inferences based on observations, numerical data, and prior knowledge to form a conclusion.
• Scientists strive to be unbiased as possible.
• Objective observations have no personal biases and are the same for all individuals, based on verifiable facts.
• Subjective observations are biased because they involve feelings and beliefs and are not the same for all individuals.
• Qualitative are descriptions based on non-numerical data, such as words, sketches, and images.
• Quantitative are observations based on numerical data using tools, instruments, and machines. Measurements are collected in the field or samples are analyzed in a lab.
• Geology relies on observations and natural facts.

Principle of Uniformitarianism

• The processes at work today are the same as how they worked in the past, which means that "the present is the key to the past".

Investigating Geologic Questions and the Crater Formation

• Investigations involve observations and measurements leading to questions and interpretations.
• Observed rocks at the rim of the crater include angular blocks of fractured shattered limestone and sandstone.
• Presence of tiny minerals that occur under very high pressures and meteorites around the crater
• The rock layers are the same type found beneath the region and the crater is within sedimentary layers.
• This demonstrates that the evidence indicates a meteor impact.
• Scientific foundations were developed in the 17th and 18th centuries.

Nicolaus Steno and the Law of Superposition

• Nicolaus Steno (1638-1686) studied geology and anatomy.
• He proposed the law of superposition, which states that in undisturbed layers of rock, the oldest layers are at the bottom and the youngest at the top.
• His 1667 classic demonstration showed that fossils represent the remains of ancient animals.

James Hutton and Charles Lyell

• James Hutton (1726–1797) is the "Father of Modern Geology”.
• Hutton is credited with the "Theory of the Earth" in 1795, which included of the rock cycle.
• Sir Charles Lyell (1797-1875) published "Principles of Geology" and "Elements of Geology" in the 1830s.
• Lyell promoted acceptance of ___ by the scientific community and public.

Earth's Formation and Structure

• By ____: materials separate based on ____.
• Primitive planets start off homogeneous.
• Shortly after a planet forms, it will differentiate into layers.
• Dense material sinks to the center, and light material floats to the top.
• Chemical layers are defined by average composition.
• The planet's physical layers are defined by physical properties.
• Convection/movement of ____ produces electrically conducting fluid generating Earth's magnetic field called the ____.

Earth's Physical and Compositional Layers

• Lithosphere is the crusts + upper mantle, and is the outermost layer.
• Strong, rigid, brittle, and broken into plates.
• Asthenosphere is the base of the lithosphere from 410-660 km.
• It is weak, solid but flows (ductile).
• Mesosphere is the base of the asthenosphere to the core boundary.
• The mesosphere is more rigid and immobile than the asthenosphere.
• Outer core: liquid
• Inner core: solid

Plate Tectonics and Isostasy

• Plate tectonics is the theory that the outer layer of the Earth (the lithosphere) is broken into several plates that move relative to one another.
• The difference in height and thickness of each block relative to other determine their elevation
• Isostasy is the relationship between crustal thickness, density, and elevation; oceanic crust is denser than continental crust.

The Rock Cycle

• The rock cycle is the process in which a rock can be moved from one place to another or converted into a different type of rock.
• The three major rock categories are sedimentary, igneous, and metamorphic.
• Sedimentary rocks form from the weathering/breakdown of preexisting rocks and the accumulation of sediments on Earth's surface.
• Igneous rocks form from the crystallization and solidification of magma and lava, while volcanic ignition rocks form on Earth's surface.
• Metamorphic rocks form from the alteration of preexisting rocks due to increase in temperature and pressure.

Earth's System and Reservoirs

• Earth's system is the sum of the physical, chemical, and biological processes operating on and within the Earth, including the geosphere, atmosphere, biosphere, hydrosphere, and cryosphere.
• Earth's spheres are a combination of systems that interact and influence one another via complex relationships.
• Interaction between systems involves the cycling of elements, such as oxygen, hydrogen, carbon, nitrogen, and phosphorous.
• Cycling of elements occurs through biogeochemical processes, which are biotic and involve organisms, and geochemical processes, which are abiotic
• Reservoirs are places where elements are stored in the Earth system, e.g., rocks, oceans, the atmosphere, plants, and animals.
• Transport pathways are the mechanisms/processes that move elements between the reservoirs, such as evaporation, precipitation, chemical weathering of rocks, volcanic outgassing, and photosynthesis.
• The hydraulic cycle describes the movement of H2O (liquid, solid, gas) through Earth's 5 spheres and involves precipitation and volcanoes.

Geologic Time Scale and Earth History

• The geologic time scale reflects major episodes in Earth's development, including continental positions (plate tectonics), life, and climate.
• First built using fossils, relative dating methods, and numeric ages.
• Geologists strive to establish the order of events throughout Earth's 4.6 billion years.
• William Smith (1790's) observed similar rocks in different areas, consistent sequences of rock layers, and different fossils in different rock layers.
• He made the 1st geologic map of Britain, noting that layers contained a predictable succession of fossils
• The geologic time scale is a 4.6 Ga calendar of Earth's history.
• The divisions of the Geologic Time Scale ranges from Eons to Era to Periods, Epochs, and Ages.