Physical Geology PDF

**PHYSICAL GEOLOGY** - Examines materials composing the Earth - Processes involve in the formation of Earth materials - Sand stone measured 2mm - Rocks composed of minerals - Mineral composed of atoms. **HISTORICAL GEOLOGY** - Studies the origin of the Earth. - The earth is abo...

**PHYSICAL GEOLOGY** - Examines materials composing the Earth - Processes involve in the formation of Earth materials - Sand stone measured 2mm - Rocks composed of minerals - Mineral composed of atoms. **HISTORICAL GEOLOGY** - Studies the origin of the Earth. - The earth is about 4.6 billion years old - Human beings have been around for only the past 2 million years. - Mankind has only witnessed 0.043%. of Earth history - The first multi-celled organisms appeared about 700 million years ago. PHYSICAL PROCESS 2 TYPES **SLOW PROCESS** - Formation of rocks - Weathering - Diagenesis - Metamorphism - Tectonism - Mountain Building **RAPID PROCESS** - Beach erosion during storm - Volcanic cone construction - Landslide - Dust storms - Mud Flows - Debris avalanche GEOLOGY PEOPLE AND ENVIRONMENT - Many of the problems and issues addressed by geology are of practical value to people. e.g. Geohazards Natural hazards are part of living on Earth Affects millions of people worldwide **some hazardous Earth process** - Volcanic eruption - Flooding - Landslide - Earthquake **Masara Landslide last Feb 6, 2024** The Incident buried numerous structures, including the barangay hall, three service buses, a jeepney, and dozens of houses. As of February 21, 2024, a total of 93 deaths were confirmed, 4 body parts retrieved, 8 missing, and 32 rescued (all injured) **➤ Geologic hazards** are natural processes. According to Ritchie et. al., more than half of the world\'s population now live in urban areas **➤ Coastal sites** are now becoming more vulnerable to geologic hazards because of development. ➤ **Sea level** rise due to global warming. ➤ **Megacities** are also exposed to seismic and volcanic hazards. E.g. is Davao City. ➤ **Mangroves** are natural defenses against wave actions Resources represent another important focus of geology. They include: - Water - Soil - Metallic minerals - Non-metallic minerals - Energy Geology deals not only with the formation and occurrence of vital resources but also in [maintaining supplies and environmental impact of their extraction.] ➤ Humans can dramatically influence geologic processes. ➤ Natural processes do not always adjust to [artificial changes] in ways that we can anticipate. ➤ **2300 years ago** ✓ Writings about fossils, gems, earthquakes and volcanoes ✓ The most influential Greek philosopher during this time is Aristotle ✓ Experiment not based on keen observation and experiments ✓ Aristotle believed that rocks were formed under the influence of the stars. ➤ **Nicolas Steno (1638-1686)** ✓ 17th century was important time in the development of Geology as a science because of the widely circulated writings of Nicolas. ✓ 3 fundamental geologic principles: - Superposition - Original Horizontality - Lateral continuity ➤ **Principle of Superposition** ✓ In an undisturbed succession of sed rock layers, the bottom is oldest and the top is the youngest. ✓ Basis for the relative-age determinations of strata and their contained fossils. ➤ **Principle of Original Horizontality** ✓ Sedimentary rocks are originally deposited horizontally **➤ Principle of lateral continuity** ✓ States that sediment extends laterally in all directions until it thins and pinches out or terminates against the edge of the depositional basin. **James Hutton (1726-1797)** ✓ Scottish geologist ✓ Founder of modern geology ✓ Formulated the \"**Principle of Uniformitarianism**\" ✓ Credited with discovering the **principle of cross-cutting** **relationships** **➤ Principle of cross-cutting relationships** ✓ Igneous intrusion/fault must be younger than the rocks it intrudes or displaces. **Charles Lyell (1797-1875)** ✓ Scottish geologist ✓ The principal advocate and interpreter of uniformitarianism ✓ Proposed the **principle of inclusions** ➤ **Principle of inclusions** ✓ Inclusions or fragments in a body of rock must be older than the rock itself. ✓ Two interpretations are possible (granite and sandstone) ➤ **Catastrophism** ✓ **James Ussher** founded the concept of catastrophism ✓ An Anglican Archbishop of Armagh ✓ Respected scholar of the bible ✓ Dated Earth as a few thousand years old ✓ Age of the Earth = 4004 BC ➤ Catastrophism ✓ Believed that Earth\'s landscapes had been shaped primarily by great catastrophes. ✓ This philosophy was an attempt to fit the rates of Earth processes to the then current ideas on the age of the Earth **➤ Uniformitarianism** ✓ **James Hutton** (a Scottish physician and gentleman farmer) published Theory of the Earth in 1795. ✓ States that the physical, chemical, and biological changes that operate today also operated in the geologic past ✓ The present is the key to the past ➤ Uniformitarianism ✓ Prior to Hutton\'s Theory of the Earth, no one had effectively demonstrated that geological processes can continue over extremely long periods of time. ➤ Uniformitarianism ✓ \"We have a chain of facts which clearly demonstrates\... that the materials of the wasted mountains have traveled through the rivers\"; and further, \"There is not one step in all this progress\... that isnot to be actually perceived.\" ✓ \"What more can we require? Nothing but time\" **PHILOSOPHY OF SCIENCE** Science: is a systematic discipline that builds and organizes knowledge in the form of testable hypotheses and predictions about the world. ➤ Two parts: **Knowledge** - information, concepts, and understanding that are accumulated over time through research and investigation **Approach** - refers to the systematic methods and processes used to acquire and validate knowledge. ➤ **A common approach and philosophy** unite the great diversity of fields that we collectively call science. ➤ **Chemist vs. Botanist** (in terms of tools and methods) ✓ Understanding ✓ Method ➤ **Scientific Method**: is a systematic approach used s to investigate natural phenomena, acquire new knowledge, or correct and Integrate previous knowledge, It involves a series of steps designed to ensure that scientific investigations are rigorous, objective, and reproducible. Scientific Method: 1\. Observation: Gather data 2\. Question: Problem identification 3\. Hypothesis: \"Educated guess\" 4\. Experiment: Test the hypothesis 5\. Analysis: Data examination 6\. Conclusion: Draw conclusion based on the analysis 7\. Communication: Sharing with the scientific community through reports. Science deals in only 2 quantities: ➤ **Observation**: Measurements, data, analyses, experiments (at present time) ✓ Verification**: Independent replication** ✓ Even replication does not guarantee that an observation is correct. ➤ **Theory: models, hypothesis** ✓ Observation form the basis of theories Scientific understanding is achieved by constructing and modifying theories to explain observation ➤ **Theories** ✓ Good theories explain existing observations and make predictions about the outcome of still unperformed experiments/observations.