Birth of Modern Geology PDF

HELLO EVERYONE! SEPTEMBER 9, 2024 MONDAY  OBJECTIVES Identify the key figures who contributed 01 to the birth of modern geology. Describe the principles of radiometric 02 dating and how it is used to determine the age of rocks, fossils, and artifacts. ...

HELLO EVERYONE! SEPTEMBER 9, 2024 MONDAY  OBJECTIVES Identify the key figures who contributed 01 to the birth of modern geology. Describe the principles of radiometric 02 dating and how it is used to determine the age of rocks, fossils, and artifacts.  BIRTH OF MODERN GEOLOGY LESSON 2.2 Before the late 1700s, people explained the Earth’s features using stories and religious beliefs. But the, scientists started looking at rocks and fossils, and they realized that the earth was much older and had changed over a very long time. James Hutton (1726-1797) was a Scottish geologist, agriculturalist, chemical manufacturer, naturalist, and physician. He is often called as the “Father of Modern Geology”. Charles Lyell (1797-1875) was a prominent Scottish geologist who played a pivotal role in shaping our understanding of Earth’s history. He is best known for his influential work “Principle of Geology”.  UNIFORMITARIANISM Uniformitarianism is the idea that the geological processes we observe currently, like erosion, sedimentation, and volcanic activity, have been happening in much the same way throughout Earth's history.  Early Methods of Dating the Earth: 1 Sedimentation Rates 2 Ocean Salinity (Salt Clock) 3 Earth’s Heat Loss  Early Methods of Dating the Earth: Sedimentation Rates Some geologists maintained that if they could determine the rate that sediments accumulate, and could ascertain the total thickness of sedimentary rocks during earth’s history, then they could estimate the length of geologic time. All that they had to do was to divide the rate of sediment accumulation by the total thickness of the sedimentary rock.  Early Methods of Dating the Earth: Ocean Salinity (Salt Clock) Scientists who subscribe to this method believed that the oceans started as fresh waters. The idea behind this method was that rivers continuously carry dissolved salts from weathered rocks into the ocean. Since these salts are not easily removed, the ocean's salinity should increase over time.  Early Methods of Dating the Earth: Earth’s Heat Loss It focused on the idea that Earth was initially a molten ball and has been gradually cooling down ever since. By measuring the current rate of heat loss from Earth's interior and assuming a constant cooling rate, scientists could theoretically calculate how long it took for the planet to reach its current temperature. Lord Kelvin, born William Thomson in 1824, was a prominent British physicist and mathematician who made significant contributions to thermodynamics and electromagnetism. One of his most famous endeavors was calculating the age of the Earth based on its cooling rate. Kelvin's calculations were rooted in the principles of thermodynamics, particularly the concept of heat conduction. Why Kelvin's Estimates Were Widely Accepted? Reputation Novelty of the Approach Alignment with Prevailing Understanding  Limitations of Kelvin's Assumptions Missing Heat Source: Kelvin's primary assumption was that the Earth was cooling solely through conduction, neglecting any additional heat sources. He didn't account for the internal heat generated by radioactive decay, which was unknown at the time.  Limitations of Kelvin's Assumptions Uniform Temperature: He also assumed a uniform temperature distribution within the Earth's interior, ignoring the potential contribution from radioactive decay.  Limitations of Kelvin's Assumptions Underestimated Age: These assumptions led to an underestimate of the Earth's age.  Refutation of Kelvin's Findings The discovery of radioactivity in the late 19th and early 20th centuries provided a new source of internal heat that Kelvin had not accounted for in his calculations. Radioactive decay within the Earth's crust and mantle generates heat, slowing the cooling process and significantly extending the estimated age of the Earth.  Refutation of Kelvin's Findings The discovery of radioactivity in the late 19th and early 20th centuries provided a new source of internal heat that Kelvin had not accounted for in his calculations. Radioactive decay within the Earth's crust and mantle generates heat, slowing the cooling process and significantly extending the estimated age of the Earth.  Refutation of Kelvin's Findings As a result, Kelvin's estimates were eventually refuted, and modern science now places the Earth's age at approximately 4.5 billion years. This discrepancy highlighted the importance of considering all possible factors in scientific calculations and demonstrated the evolving nature of scientific understanding.  The Discovery of Radioactivity A New Era of Dating: Radioactivity  Introduction to the Concept of Radioactivity The discovery of radioactivity at the end of the 19th century marked a significant turning point in the field of science, particularly in our understanding of the Earth's age and the dating of geological and archaeological materials. Radioactivity refers to the spontaneous emission of particles or radiation from the nucleus of an unstable atom. This process, first observed by Henri Becquerel and later studied extensively by Marie and Pierre Curie, revealed that certain elements could change into other elements over time, releasing energy in the form of radiation. This phenomenon provided a new tool for scientists to measure time, revolutionizing dating methods. Parent and Daughter Isotopes Radioactive Decay: In radioactive decay, the original unstable atom is known as the "parent" isotope, and the product of its decay is called the "daughter" isotope.  Transformation: The parent isotope decays into the daughter isotope at a predictable rate. This transformation occurs through various processes, such as alpha decay, beta decay, or gamma decay, each involving the emission of different particles or energy. Relationship: The relationship between the parent and daughter isotopes is crucial for dating because it allows scientists to calculate the age of a sample based on the proportion of remaining parent isotopes to the amount of daughter isotopes produced. Importance of Radioactive Decay Rates for Dating Half-Life: The key to using radioactivity for dating lies in the concept of the half- life, which is the time it takes for half of the parent isotopes in a sample to decay into daughter isotopes. Radiometric Dating: By measuring the ratio of parent-to-daughter isotopes and knowing the half-life of the parent, scientists can determine the age of a sample with remarkable precision. This method, known as radiometric dating, has been instrumental in establishing the ages of rocks, fossils, and even the Earth itself.  Radioactive Decay the emission of energy in the form of ionizing radiation. It is also measured in terms of half- life A half-life is the time it takes for one half of the radioactive materials to decay. Half- lives are computed from laboratory analysis of radioactive elements. As these decay, the amount decreases. If the trunk of a tree is already very old and the amount of radioactive carbon is too small, then the tree trunk cannot be dated by carbon 14 method. carbon 14 dating cannot be used if the tree trunk is less than 100 years old. In order to use the half-life method, scientists assume a "closed system"  where there is nothing added or lost in terms of the radioactive element samples or other elements used in the laboratory analysis. THANK YOU!