ESS 101 Exam 2 review - Geologic Time Know age of the...

This preview shows page 1 - 3 out of 9 pages.

Geologic Time Know age of the universe and age of the earth Universe 13.8 billion years old Earth is 4.6 billion years old Know in which era (not absolute dates) significant events in the history of the earth occurred. Cenozoic (66 ma to present) o Age of mammals, birds and flowering plants o Pleistocene life: the ice age Giant Pleistocene Beaver (8 ft long) Mammoth o Early Hominids: Australopithecus afarensis “Lucy” (monkey type of thing) Circa 3.8 Ma 4 feet tall, female, stood on two legs Mesozoic o Mid-Triassic: first dinosaurs and mammals o Jurassic: dinosaur/bird o Cretaceous: t-Rex, triceratops o 66 Ma: extinction of dinosaurs Purgatorius: rat like animal that belongs to group of early mammal’s ancestor to all primates Paleozoic o Cambrian explosion: sudden appearance of large number is multicellular organisms with hard parts Silurian: first fish, crawling insects and vascular plants Devonian: first amphibians, seed plants and flying insects Permian: Africa and North America collide to form Pangea - Permian extinction 251 Ma; largest mass extinction in earths history (96% of marine species and 70% of land species extinct). Know what Uniformitarianism is Earths geologic processes acted in the same manner with same intensity in the past as they do in the present (geologic processes haven't changed) Know the difference between relative and absolute age dates. Relative age dating : when something formed or happened in relation to other things; the order of events or objects, from oldest to youngest o Determined by applying simple principles or “laws Absolute age dating : when something formed or happened in exact units of time (days, months, years) o Determined using radiometric dating Know the relative age dating laws
Image of page 1

Subscribe to view the full document.

1. Organize horizontally: Sedimentary beds are deposited horizontally 2. Superposition: Within an undisturbed sequence of sedimentary or volcanic rocks, layers get younger from bottom to top 3. Inclusions: an inclusion is older than the rock it is within 4. Cross cutting relations: a feature can only cut through a rock that exits (is older than itself) o Intrusions and faults are younger than the rocks they cut through Know the 3 types of unconformities and how to ID them Unconformities: Gaps in the Geologic Record o An erosional surface or non-deposition. Gap in rock record = gap in time Types of unconformities 1.
Image of page 2
Image of page 3

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern