Earth, Principles, Time Review Lec 2 PDF
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This document is a study guide for a lecture, outlining key concepts and principles of Earth science and geologic time scale, including the Nebular Hypothesis, the layers within the Earth, and the principles of original horizontality, superposition, and uniformitarianism. It describes the different types of unconformities and the importance of fossils in understanding geological history.
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Week 1 -‐‑ Lecture 2 STUDY GUIDE The Dynamic Planet Slide 5 – Know the 4 “spheres”: hydrosphere (water) ...
Week 1 -‐‑ Lecture 2 STUDY GUIDE The Dynamic Planet Slide 5 – Know the 4 “spheres”: hydrosphere (water) atmosphere (air) biosphere (organisms) lithosphere (solid rock) Slide 8 – Know terms: Hydrologic cycle and Rock Cycle Slide 10 – Astronomers believe the Big Bang (when the universe began) occurred 13.7 Billion years ago. Slide 13 – 14 – Nebular Hypothesis for the formation of our Solar System (~5 billion years ago) 1. Interstellar cloud of gas and dust 2. As the cloud rotates – it contracts and rotation speeds up (gravitational attraction). It becomes a flat disk with matter concentrated at the center 3. Sun forms at the center from intensely concentrated matter there. Nuclear reaction expels matter into orbits around the new star. 4. The planets form by cooling and concentration of matter within orbital rings around the new star, like snowballs gathering material along rings. Terrestrial planets (Mercury, Venus, Earth, Mars) = inner rocky planets Jovian planets (Jupiter, Saturn, Uranus, Neptune) = outer gas giants Slide 18 – Be able to list the layers within the Earth in order from surface going inward: Lithosphere, Asthenosphere, Mesosphere), Outer Core, Inner Core. Be able to identify these on a diagram of the Earth. Slide 21 – The Earth is believed to be 4.6 Billion years old. Oldest Rocks = 4.4 Billion years old – (Zircons found in Australia – Slide 22) Slide 27 – Be able to identify the Principle of Uniformitarianism: “The Present is the Key to the Past” Slide 29 – Know: Principle of Original Horizontality: Sedimentary rocks are deposited in horizontal layers If rocks are not horizontal – something happened later Slide 33 – Know: Principle of Superposition In undisturbed rocks – the youngest rocks are found on top (layers of cake) Slide 36 – Know: Principle of Cross-‐‑cutting relationships 1. igneous rocks cut across previously existing rock – so are younger 2. Faults and Unconformities are younger than original sedimentary layers Slide 40 – Unconformities = gaps in geologic record due to (1) no deposition (2) erosion of rocks that were already present. (3) They are recognized by different: (a) orientation of rocks, (b) types of fossils, (c) type of rocks Slide 44 – Be able to identify the 3 types of unconformities: 1. Angular unconformity: sediments above sediments at an angle 2. Nonconformity: Sediments on igneous and metamorphic rocks 3. Disconformity: sediments on top of other sediments with time gap Slide 45 – Given a diagram like this one on an exam -‐‑ be able to state which are older and which are younger events Slide 46 – Fossils are remains of plants or animals or their activities Slide 53 – Know: Principle of faunal succession: specific group[s) of fossils follow one another in the rock record. Slide 65 – Know definition of “half-‐‑life” = amount of time it takes for half of a parent atom to decay to a daughter atom. Slide 74 – EXTRA CREDIT QUESTION ON EXAM #1 Geologic Time Scale – be able to list in order from oldest to youngest the 7 Periods in the Paleozoic Era. YOUNGEST Permian Pennsylvanian Mississippian Devonian Silurian Ordovician Cambrian OLDEST
