earth science Dynamic planet complete presentation.pptx

Earth science concepts in environmental science
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geological time

1. The Dynamic Planet Geologic Time and Change Lecture 2 and 3 Department of Environmental Sciences, KIU BS: 2 nd semester, 2023 Resource Person: Dr.Karamat Ali

2. Geologic Time and Change

3. Lecture outline Introduction Geologic Time and Change Priniciple of Uniformitarianism

4. Earth’s endogenic system S olid portion of Earth, broadly called the lithosphere P rocesses operating in Earth’s interior, driven by heat from deep within the planet B uilding of mountains and the dramatic volcanic eruptions that bring molten materials to Earth’s surface Earth’s exogenic system Processes that wear away (left) Earth’s surface E xternal processes produce landscapes

5. Geology……….. all aspects of Earth—its history, composition and internal structure, surface features, and the processes acting on them Physical geography………the study of Earth’s surface landforms—specifically, their origin, evolution, form, and spatial distribution Geomorphology is a subfield of both geology and physical geography

6. Dividing Earth history into time intervals Geologist have divided Earth’s history into a series of time intervals Time intervals are not equal in length like the hours in a days Time intervals are variable in length Geological time is divided using significant events in the history of Earth Geologic Time Scale

7. Scale breaks the past 4.6 billion years down into several time spans Eons are the largest time span, although some refer to the Precambrian as a super-eon . S horter time spans within eons are eras, periods, and epochs. Major events in Earth’s history determine the boundaries between these intervals, which are not equal in length.

8. The geologic time scale (GTS) is a system of chronological dating that classifies geological strata (stratigraphy) in time It is used by geologists, paleontologists (study of fossils), and other Earth scientists to describe the timing and relationships of events in geologic history .

9. To divide Earth’s long geologic history (a) the geologic time scale divides Earth geological history into intervals of time defined by major events or change on Earth ( E arth evolution , origin of organism, extinction of organisms) (b) The larges unit of geological time is an Eon (for example in day largest is day same as in Eon is time unit in the geological history ) (c ) Earth’s 4.6 billion year history is divided into eons: The Hadean, Archean, Proterozoic and Phanerozoic (d) The Hadean, Archean, and Proterozoic eons together are called Precambrian time

10. Geological time Scale. Eon… (1.1)Hadean…..Earth Forms…4.5 billions years ago (1.2) Archean…Oldest rock, Earth crust forms..4.0 billions years ago (1.3) Proterozoic…life begins in Sea…2.5 billions years ago (1.4) Phanerozio..542 millions years ago Note: All/combine four Eon called Prcambrain (The Ear of early life)

11. Geological time Scale. Eon… (1.1)Hadean…..Earth Forms…4.5 billions years ago (1.2) Archean…Oldest rock, Earth crust forms..4.0 billions years ago (1.3) Proterozoic…life begins in Sea…2.5 billions years ago (1.4) Phanerozioc..542 millions years ago Note: All/combine four Eon called Prcambrain (The Ear of early life) Geological time Scale. 1.4 ERA… Phanerozoic 1.4.1 Paleozoic (the era of ancient life ) 1.4.2 Mesozoic(age of reptiles and gymnosperms 1.4.3 Cenozoic (age of mammals and angiosperms )

12. History of the Earth _ Hadean, Archean, and Proterozoic Eons Video https:// www.youtube.com/watch?v=DWC2lZHaq5c

13. Priniciple of Uniformitarianism Paleoclimatic techniques that establish chronologies of past environments, enabling scientists to reconstruct the age and character of past climates A ssumption of these reconstructions is that the movements, systems, and cycles that occur today also operated in the past This guiding principle of Earth science, called uniformitarianism, presupposes that the same physical processes now active in the environment were operating throughout Earth’s history The phrase “ the present is the key to the past” describes the principle

14. For example, the processes by which streams carve valleys at present are assumed to be the same as those that carved valleys 500 million years ago. Evidence from the geologic record, preserved in layers of rock that formed over millennia, supports this concept, which was first hypothesized by geologist James Hutton in the 18th century and later amplified by Charles Lyell in his influential book Principles of Geology (1830

15. The Present is the Key to the Past Many geologists consider James Hutton (1726–1797) to be the father of historical geology. Hutton observed such processes as wave action, erosion by running water, and sediment transport and concluded that given enough time these processes could account for the geologic features in his native Scotland. He thought that “the past history of our globe must be explained by what can be seen to be happening now.” This assumption that present-day processes have operated throughout geologic time was the basis for the principle of uniformitarianism.

16. A diabase dike at Hance Rapid on the Colorado River cross-cuts the Hakatai Shale. Grand Canyon National Park, Arizona.

17. P rinciple of uniformitarianism applies mainly to the gradual processes of geologic change, it also includes sudden, catastrophic events such as massive landslides, earthquakes, volcanic eruptions, and asteroid impacts E vents have geological importance and may occur as small interruptions in the generally uniform processes that shape the slowly evolving landscape U niformitarianism means that the natural laws that govern geologic processes have not changed throughout geologic time even though the rate at which these processes operate is variable

18. Relative Age and the Principle of Superposition Geologists assign ages to events or specific rocks, structures, or landscapes using the geologic time scale, based on either relative time (what happened in what order) or numerical time (the actual number of years before the present) Relative age refers to the age of one feature with respect to another within a sequence of events. In rocks, relative age refers to the relative positions of rock layers, or strata, within a sequence.

19. S cientific study of the order and relative position of rock sequences is stratigraphy. Within rock strata, clues such as fossils indicate the environment during rock formation Determinations of relative age are based on the principle of superposition, which states that rock and unconsolidated particles are deposited with the youngest layers “superposed” toward the top of a rock formation and the oldest at the base

20. Numerical Age and Radiometric Dating Numerical age (sometimes called absolute age) is today determined using isotopic dating techniques and other scientific methods. The technique of radiometric dating, for example, uses the rate of decay for different unstable isotopes to provide a steady time clock to pinpoint the ages of Earth materials. Precise knowledge of radioactive decay rates allows scientists to determine the date a rock formed by comparing the amount of original isotope in the sample with the amount of decayed end product in the sample Numerical ages permit scientists to refine the geologic scale and improve the accuracy of relative dating sequences. Isotopes are distinct nuclear species of the same element . Atoms with the same number of protons but different numbers of neutrons are called isotopes

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22. Assignment number 2 Draw sketch of geological time scale