DOCSLIB.ORG

Mesozoic ­ Accessscience from Mcgraw­Hill Education

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mesozoic ­ Accessscience from Mcgraw­Hill Education 5/10/2016 Mesozoic ­ AccessScience from McGraw­Hill Education (http://www.accessscience.com/) Mesozoic Article by: Dubiel, Russell F. U.S. Geological Survey, U.S. Department of the Interior, Denver, Colorado. Publication year: 2014 DOI: http://dx.doi.org/10.1036/1097­8542.417200 (http://dx.doi.org/10.1036/1097­8542.417200) Content Triassic Jurassic Cretaceous Bibliography Additional Readings The middle era of the three major divisions of the Phanerozoic Eon (Paleozoic, Mesozoic, and Cenozoic eras) of geologic time, encompassing an interval from 251 to 65 million years ago (Ma) based on various isotopic­age dates. The Mesozoic Era is known also as the Age of the Dinosaurs and the interval of middle life. The Mesozoic Erathem (the largest recognized time­stratigraphic unit) encompasses all sedimentary rocks, body and trace fossils of organisms preserved, metamorphic rocks, and intrusive and extrusive igneous rocks formed during the Mesozoic Era. http://www.accessscience.com/content/mesozoic/417200 1/11 5/10/2016 Mesozoic ­ AccessScience from McGraw­Hill Education The Mesozoic Era was originally named for one of three principal divisions of the fossil record, or history of life, that was bounded before and after by significant mass extinctions that dramatically changed the biotic composition of the world. In England during the early 1840s, geologist John Phillips introduced the terms Mesozoic Era and Cenozoic Era, in conjunction with geologist Adam Sedwick's term Paleozoic Era, proposed in 1838, to denote the widespread observation that three successive and distinct biotic assemblages were preserved in the fossil record. The Mesozoic Era comprises life intermediate in kind between ancient life­forms (Paleozoic Era) and recent life­ forms (Cenozoic Era). See also: Cenozoic (/content/cenozoic/118600); Paleozoic (/content/paleozoic/484300) The Mesozoic Era records dramatic changes in the geologic and biologic history of the Earth. At the beginning of the Mesozoic Era, all the continents were amassed into one large supercontinent, Pangaea. Both the marine and continental biotas were impoverished from the mass extinction that marked the boundary between the Permian and Triassic periods, and the end of the Paleozoic Era. This mass extinction was responsible for the loss of over 90% of the species on Earth. During the Mesozoic Era, many significant events were recorded in the geologic and fossil record of the Earth, including the breakup of Pangaea and the evolution of modern ocean basins by continental drift, the rise of the dinosaurs, the ascension of the angiosperms (flowering plants), the diversification of the insects and crustaceans, and the appearance of the mammals and birds. The end of the Mesozoic Era is marked by a major mass extinction at the Cretaceous­Tertiary boundary that records several meteorite impacts, the extinction of the dinosaurs, the rise to dominance of the mammals, and the beginning of the Cenozoic Era and the life­forms dominant today. See also: Continental drift (/content/continental­drift/159000); Plate tectonics (/content/plate­tectonics/527000) http://www.accessscience.com/content/mesozoic/417200 2/11 5/10/2016 Mesozoic ­ AccessScience from McGraw­Hill Education The Mesozoic Era comprises three periods of geologic time: the Triassic Period (251–200 Ma), the Jurassic Period (200–146 Ma), and the Cretaceous Period (146–65 Ma) [Fig. 1]. These periods are each subdivided into epochs, formal designations of geologic time described as Early, Middle, and Late (except for the Cretaceous, which has no middle epoch designated yet). The packages of rock themselves are subdivided into series designated Lower, Middle, and Upper (except for Cretaceous). Each epoch is subdivided into ages. Likewise, each series is subdivided into stages, which are time­stratigraphic units whose boundaries are based on unconformities, hiatuses, or erosional surfaces, on correlations to a type section (where rocks are first described), or preferably on changes in the biota that depict true measurable time (for example, evolutionary changes). See also: Unconformity (/content/unconformity/720400) http://www.accessscience.com/content/mesozoic/417200 3/11 5/10/2016 Mesozoic ­ AccessScience from McGraw­Hill Education Fig. 1 Subdivisions of the Mesozoic Era, including the best age estimates and the eustatic sea­level curve depicted as relative change in coastal onlap as the shoreline moved landward (sea­level rise) or seaward (sea­level fall). http://www.accessscience.com/content/mesozoic/417200 4/11 5/10/2016 Mesozoic ­ AccessScience from McGraw­Hill Education The correlations of time equivalency and age dating in the Mesozoic Era have been accomplished by utilizing biostratigraphic zones based on individual fossil groups or by an acme or composite zonal assemblage based on numerous fossil groups. Marine and continental fossil groups used to describe chronologically Mesozoic rocks include marine foraminifera and nannofossils (shelled protozoa), ammonites (cephalopods), and inoceramids (mollusks); continental plant spores and pollen (palynology); dinosaurs; and mammals. Correlations based on these and other organisms in the Mesozoic Era depend on the faunal and floral succession through origination and extinction of species. See also: Cephalopoda (/content/cephalopoda/120800); Foraminiferida (/content/foraminiferida/267800); Mollusca (/content/mollusca/431300); Palynology (/content/palynology/484800) The organization of subdivisions based on physical and biological evidence allows geologists and paleontologists to describe both rocks and fossils in specific intervals of time and space. Thus, earth scientists can communicate effectively with one another and characterize more precisely the physical and biotic changes during the Mesozoic Era, as well as the other eras in geologic history. See also: Paleontology (/content/paleontology/484100); Stratigraphy (/content/stratigraphy/659000) Triassic The Mesozoic Era begins with the Triassic Period, which constitutes nearly one­third the total time of the era and is well exposed especially in Europe and North America, with other important outcrops in India, China, Argentina, and South Africa. The Triassic Period was named originally the Trias in Germany in 1834 by Friedrich August von Alberti for its unique fauna and natural division into three distinct stratigraphic units. As a result of the unique geography of the single Pangaean landmass, the alteration in oceanic currents produced around one continent, and the monsoonal climatic setting, life changed substantially in both marine and continental ecosystems. The marine ecosystems witnessed the addition of large reptiles and the modern reef­building corals, the reemergence and diversification of the mollusks, and the emergence of pelagic life in the form of planktonic organisms. Ray­finned and bony fishes and sharks dominated the seas. Placodonts and nothosaurs were aquatic marine reptiles that fed on mollusks and other marine invertebrates. Ichthyosaurs appeared in the oceans for the first time. Fresh­water and terrestrial ecosystems were marked by the emergence and diversification of the dinosaurs, flying reptiles, frogs, turtles, terrestrial crocodiles, and birds; the appearance of the mammals, though quite small in size; the emergence of freshwater and terrestrial crayfish; and the emergence of new insects, such as the Isoptera (termites), Diptera (flies), and the Hymenoptera (bees, wasps, and possibly ants), appearing earlier in the Mesozoic than previously thought. Trace fossil evidence for these new insects indicates the advent of social behavior in termites and in primitive bees, prior to the appearance of angiosperms in the Cretaceous. In terrestrial ecosystems ferns and seed ferns were abundant, but gymnosperm floras continued to dominate the landscape. Therapsids rediversified after the Permo­Triassic extinctions, and thecodonts gave rise to the crocodiles and to the first dinosaurs, which were small in stature. During the Triassic Period the continents were amassed tectonically into one great landmass, the supercontinent Pangaea, that was distributed equally across the paleoequator in both the Northern and Southern hemispheres (Fig. 2a). Since the majority of the enormous Pangaean landmass was inland from the influence of the ocean, and its configuration distributed equally across the Equator, a worldwide monsoonal climate pattern dominated during http://www.accessscience.com/content/mesozoic/417200 5/11 5/10/2016 Mesozoic ­ AccessScience from McGraw­Hill Education the Triassic that created alternating wet and dry seasons in many regions. Areas landward of the coasts experienced increased continentality of the climate and produced more pronounced wet and dry seasons. See also: Paleoclimatology (/content/paleoclimatology/483500); Paleogeography (/content/paleogeography/483800) Fig. 2 Schematic reconstruction showing paleogeography of continents, epicontinental seas, and ocean basins (arrows denote ocean currents) on Pangaea in the Mesozoic Era from the (a) Triassic (220 Ma), (b) Jurassic (155 Ma), and (c) Cretaceous (70 Ma) periods. At the end of the Triassic, Pangaea began to break apart and the monsoonal climate pattern began to disintegrate. Evidence for the breakup of Pangaea and the eventual formation of the northern Atlantic Ocean is the presence of rift basins along the east coast of North America and the northwest coast of Africa. A mass extinction defines the boundary between the end of the Triassic and the beginning of the
Load more

Recommended publications
  • Mesozoic—Dinos!
    MESOZOIC—DINOS! VOLUME 9, ISSUE 8, APRIL 2020 THIS MONTH DINOSAURS! • Dinosaurs ○ What is a Dinosaur? page 2 DINOSAURS! When people think paleontology, ○ Bird / Lizard Hip? page 5 they think of scientists ○ Size Activity 1 page 10 working in the hot sun of ○ Size Activity 2 page 13 Colorado National ○ Size Activity 3 page 43 Monument or the Badlands ○ Diet page 46 of South Dakota and ○ Trackways page 53 Wyoming finding enormous, ○ Colorado Fossils and fierce, and long-gone Dinosaurs page 66 dinosaurs. POWER WORDS Dinosaurs safely evoke • articulated: fossil terror. Better than any bones arranged in scary movie, these were Articulated skeleton of the Tyrannosaurus rex proper order actually living breathing • endothermic: an beasts! from the American Museum of Natural History organism produces body heat through What was the biggest dinosaur? be reviewing the information metabolism What was the smallest about dinosaurs, but there is an • metabolism: chemical dinosaur? What color were interview with him at the end of processes that occur they? Did they live in herds? this issue. Meeting him, you will within a living organism What can their skeletons tell us? know instantly that he loves his in order to maintain life What evidence is there so that job! It doesn’t matter if you we can understand more about become an electrician, auto CAREER CONNECTION how these animals lived. Are mechanic, dancer, computer • Meet Dr. Holtz, any still alive today? programmer, author, or Dinosaur paleontologist, I truly hope that Paleontologist! page 73 To help us really understand you have tremendous job more about dinosaurs, we have satisfaction, like Dr.
    [Show full text]
  • Asteroid Impact, Not Volcanism, Caused the End-Cretaceous Dinosaur Extinction
    Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction Alfio Alessandro Chiarenzaa,b,1,2, Alexander Farnsworthc,1, Philip D. Mannionb, Daniel J. Luntc, Paul J. Valdesc, Joanna V. Morgana, and Peter A. Allisona aDepartment of Earth Science and Engineering, Imperial College London, South Kensington, SW7 2AZ London, United Kingdom; bDepartment of Earth Sciences, University College London, WC1E 6BT London, United Kingdom; and cSchool of Geographical Sciences, University of Bristol, BS8 1TH Bristol, United Kingdom Edited by Nils Chr. Stenseth, University of Oslo, Oslo, Norway, and approved May 21, 2020 (received for review April 1, 2020) The Cretaceous/Paleogene mass extinction, 66 Ma, included the (17). However, the timing and size of each eruptive event are demise of non-avian dinosaurs. Intense debate has focused on the highly contentious in relation to the mass extinction event (8–10). relative roles of Deccan volcanism and the Chicxulub asteroid im- An asteroid, ∼10 km in diameter, impacted at Chicxulub, in pact as kill mechanisms for this event. Here, we combine fossil- the present-day Gulf of Mexico, 66 Ma (4, 18, 19), leaving a crater occurrence data with paleoclimate and habitat suitability models ∼180 to 200 km in diameter (Fig. 1A). This impactor struck car- to evaluate dinosaur habitability in the wake of various asteroid bonate and sulfate-rich sediments, leading to the ejection and impact and Deccan volcanism scenarios. Asteroid impact models global dispersal of large quantities of dust, ash, sulfur, and other generate a prolonged cold winter that suppresses potential global aerosols into the atmosphere (4, 18–20). These atmospheric dinosaur habitats.
    [Show full text]
  • The Geologic Time Scale Is the Eon
    Exploring Geologic Time Poster Illustrated Teacher's Guide #35-1145 Paper #35-1146 Laminated Background Geologic Time Scale Basics The history of the Earth covers a vast expanse of time, so scientists divide it into smaller sections that are associ- ated with particular events that have occurred in the past.The approximate time range of each time span is shown on the poster.The largest time span of the geologic time scale is the eon. It is an indefinitely long period of time that contains at least two eras. Geologic time is divided into two eons.The more ancient eon is called the Precambrian, and the more recent is the Phanerozoic. Each eon is subdivided into smaller spans called eras.The Precambrian eon is divided from most ancient into the Hadean era, Archean era, and Proterozoic era. See Figure 1. Precambrian Eon Proterozoic Era 2500 - 550 million years ago Archaean Era 3800 - 2500 million years ago Hadean Era 4600 - 3800 million years ago Figure 1. Eras of the Precambrian Eon Single-celled and simple multicelled organisms first developed during the Precambrian eon. There are many fos- sils from this time because the sea-dwelling creatures were trapped in sediments and preserved. The Phanerozoic eon is subdivided into three eras – the Paleozoic era, Mesozoic era, and Cenozoic era. An era is often divided into several smaller time spans called periods. For example, the Paleozoic era is divided into the Cambrian, Ordovician, Silurian, Devonian, Carboniferous,and Permian periods. Paleozoic Era Permian Period 300 - 250 million years ago Carboniferous Period 350 - 300 million years ago Devonian Period 400 - 350 million years ago Silurian Period 450 - 400 million years ago Ordovician Period 500 - 450 million years ago Cambrian Period 550 - 500 million years ago Figure 2.
    [Show full text]
  • Recent Advances in Studies on Mesozoic and Paleogene Mammals in China
    Vol.24 No.2 2010 Paleomammalogy Recent Advances in Studies on Mesozoic and Paleogene Mammals in China WANG Yuanqing* and NI Xijun Institute of Vertebrate Paleontology and Paleoanthropology, CAS, Beijing 10004, China ike in other fields of paleontology, research in from the articular of the lower jaw and the quadrate of the paleomammalogy mainly falls into two aspects. cranium following the process of reduction and detachment LOne is related to the biological nature of fossil from the reptilian mandible, are new elements of the bony mammals, such as their systematics, origin, evolution, chain in the mammalian middle ear. The appearance of phylogenetic relationships, transformation of key features mammalian middle ear allows mammals to hear the sound and paleobiogeography, and the other is related to the of higher frequencies than reptiles do. Generally speaking, geological context, involving biostratigraphy, biochronology, a widely accepted hypothesis is that mammals originated faunal turnover and its relations to the global and regional from a certain extinct reptilian group. The formation and environmental changes. In the last decade, a number of development of the definitive mammalian middle ear well-preserved mammalian specimens were collected from (DMME) has thus become one of the key issues in the study different localities around the country. Such discoveries have of mammalian evolution and has drawn the attention from provided significant information for understanding the early many researchers for many years. evolution of mammals and reconstructing the phylogeny of Developmental biological studies have proven the early mammals. function of the Meckel’s cartilage and its relationship to Studies of Chinese Mesozoic mammals achieved the ear ossicles during the development of mammalian remarkable progress in the past several years.
    [Show full text]
  • Making a Timeline Rope
    Making a Timeline Rope Background: Your timeline rope invites students to focus on recent periods of geologic time. This rope demonstrates four periods and seven epochs, beginning with the Jurassic Period in the Mesozoic Era, in the Phanerozoic Eon, and ending at the present time, in the Holocene Epoch, in the Quaternary Period of the Cenozoic Era, in the Phanerozoic Eon. Standards: SC.D.1.2.3 SC.D.1.2.5 SC.D.1.3.1 SC.D.1.3.2 SC.D.1.3.3 MA.1.G.5.1 MA.1.G.5.2 MA.2.G.3.4 MA.2.G.3.1 MA.3.G.5.2 MA.4.G.3.3 MA.6.A.5.1 MA.8.A.1.3 SC.912.E.5.3 SC.912.E.6.4 SC.912.E.6.5 SC.912.N.3.1 SC.912.N.3.5 Objectives: − Analyze how specific geological processes and features are expressed in Florida and elsewhere − Describe the geological development of the present day oceans and identify commonly found features − Understand the function of models in science, and identify the wide range of models used. − Compare, contrast, and convert units of measure Vocabulary: Geologists and paleontologists give names to spans of many years. Spans are approximate; they relate more to fossil age ranges than to absolute years. Experts use a common vocabulary. Eon: Largest division of geologic time. Each eon contains several periods and can last for hundreds of millions to billions of years. Some experts identify four eons. (Example: Life on earth has been abundant during the Phanerozoic Eon, as well- preserved fossils prove.) Era: Shorter than an eon.
    [Show full text]
  • Cretaceous - Tertiary Mass Extinction Meteoritic Versus Volcanic Causes
    GENERAL I ARTICLE Cretaceous - Tertiary Mass Extinction Meteoritic Versus Volcanic Causes P V Sukumaran The bolide impact theory for mass extinctions at the Cretaceous-tertiary (K-T) boundary was a revolutionary concept. This theory was contested by short duration global volcanism as a possible alternative cause for the K-T extinction. Though there is a converging evidence for an extra-terrestrial impact coinciding with the P V Sukumaran took his terminal Cretaceous, the causative link between the M Tech degree in impact and the K-T mass extinction is debatable. Thus, Applied Geology from the while the impact theory is re-emerging, available evidence University of Saugar and has been with the is still insufficient to rule out either of the two hypotheses. Geological Survey of India since 1974. His interests Introduction include geochemistry, petrology and palae­ oceanography. He is It is now widely believed that life on earth began very early in presently posted to the its geological history, probably about 4000 My (million years) Marine Wing of the ago (Mojzsis and others, 1996). Since then it underwent Department and has participated in many several evolutionary branchings to the complex diversity as scientific cruises both as we see today. Nevertheless, it was not a smooth voyage for life Chief Scientist and as a all along, the evolution was punctuated by geologically participating scientist. ins tan taneous events of mass mortality. New species emerged at the expense of their predecessors following each extinction event and life went on evolving ever more vibrantly. In the geologic record of rock strata, such mass extinction events are identifiable based on sudden absence and reduction in diversity of fossil assemblage across stratigraphic boundaries.
    [Show full text]
  • Uncorking the Bottle: What Triggered the Paleocene/Eocene Thermal Maximum Methane Release? Miriame
    PALEOCEANOGRAPHY, VOL. 16, NO. 6, PAGES 549-562, DECEMBER 2001 Uncorking the bottle: What triggered the Paleocene/Eocene thermal maximum methane release? MiriamE. Katz,• BenjaminS. Cramer,Gregory S. Mountain,2 Samuel Katz, 3 and KennethG. Miller,1,2 Abstract. The Paleocene/Eocenethermal maximum (PETM) was a time of rapid global warming in both marine and continentalrealms that has been attributed to a massivemethane (CH4) releasefrom marine gas hydrate reservoirs. Previously proposedmechanisms for thismethane release rely on a changein deepwatersource region(s) to increasewater temperatures rapidly enoughto trigger the massivethermal dissociationof gas hydratereservoirs beneath the seafloor.To establish constraintson thermaldissociation, we modelheat flow throughthe sedimentcolumn and showthe effectof the temperature changeon the gashydrate stability zone throughtime. In addition,we provideseismic evidence tied to boreholedata for methanerelease along portions of the U.S. continentalslope; the releasesites are proximalto a buriedMesozoic reef front. Our modelresults, release site locations, published isotopic records, and oceancirculation models neither confirm nor refute thermaldissociation as the triggerfor the PETM methanerelease. In the absenceof definitiveevidence to confirmthermal dissociation,we investigatean altemativehypothesis in which continentalslope failure resulted in a catastrophicmethane release.Seismic and isotopic evidence indicates that Antarctic source deepwater circulation and seafloor erosion caused slope retreatalong
    [Show full text]
  • A Fundamental Precambrian–Phanerozoic Shift in Earth's Glacial
    Tectonophysics 375 (2003) 353–385 www.elsevier.com/locate/tecto A fundamental Precambrian–Phanerozoic shift in earth’s glacial style? D.A.D. Evans* Department of Geology and Geophysics, Yale University, P.O. Box 208109, 210 Whitney Avenue, New Haven, CT 06520-8109, USA Received 24 May 2002; received in revised form 25 March 2003; accepted 5 June 2003 Abstract It has recently been found that Neoproterozoic glaciogenic sediments were deposited mainly at low paleolatitudes, in marked qualitative contrast to their Pleistocene counterparts. Several competing models vie for explanation of this unusual paleoclimatic record, most notably the high-obliquity hypothesis and varying degrees of the snowball Earth scenario. The present study quantitatively compiles the global distributions of Miocene–Pleistocene glaciogenic deposits and paleomagnetically derived paleolatitudes for Late Devonian–Permian, Ordovician–Silurian, Neoproterozoic, and Paleoproterozoic glaciogenic rocks. Whereas high depositional latitudes dominate all Phanerozoic ice ages, exclusively low paleolatitudes characterize both of the major Precambrian glacial epochs. Transition between these modes occurred within a 100-My interval, precisely coeval with the Neoproterozoic–Cambrian ‘‘explosion’’ of metazoan diversity. Glaciation is much more common since 750 Ma than in the preceding sedimentary record, an observation that cannot be ascribed merely to preservation. These patterns suggest an overall cooling of Earth’s longterm climate, superimposed by developing regulatory feedbacks
    [Show full text]
  • Late Cretaceous (Santonian-Campanian) Stratigraphy of the Northern Sacramento Valley, California
    Late Cretaceous (Santonian-Campanian) stratigraphy of the northern Sacramento Valley, California DcT^rf {Department of Geology, University of California at Davis, Davis, California 95616 rElbK L). WAKL) J ABSTRACT INTRODUCTION METHODS The Upper Cretaceous (Coniacian-lower Thick accumulations of Upper Cretaceous Strata of the Chico Formation dip gently to Campanian) Chico Formation of the north- sedimentary deposits are found on the western, the southwest. Sections were mejisured using eastern Sacramento Valley, California, includes northern, and eastern margins of the Great Val- either tape and compass or Jacob's staff. In some three newly defined members at the type local- ley of California (Fig. 1). The search for oil and areas, outcrop data were plotted on U.S. Geo- ity: (1) cobble conglomerate of the basal Pon- gas in northern California, as well as interest in logical Survey topographic quadrangles and derosa Way Member, (2) coarse-grained con- the processes of sedimentation in fore-arc re- stratigraphie columns were determined trigo- glomeratic sandstone of the overlying Musty gimes, has made the Great Valley seque nce, ex- nometrically. Paleontologic collections of mac- Buck Member, and (3) fine-grained silty sand- posed along the west side of the Sacramento rofossils were made during the measuring of stone of the uppermost Ten Mile Member. Valley, probably the best-studied fore-arc de- sections. Minor offset of bedding was observed Other outcrops of the Chico Formation exhibit posit in the world (Ojakangas, 1968; Dickinson, on more southerly exposures of the Chico For- the same three members plus an additional unit, 1971; Ingersoll, 1978, 1979). These workers in- mation, and such structural modification be- the Kingsley Cave Member, composed of mud- terpreted strata of the Great Valley sequence to comes more prominent farther north.
    [Show full text]
  • Reconstructions of the Continents Around the North Atlantic at About the 60Th Parallel
    CORE Metadata, citation and similar papers at core.ac.uk Provided by RERO DOC Digital Library 1 Published in Earth and Planetary Science Letters 187: 55-69, 2001 Reconstructions of the continents around the North Atlantic at about the 60th parallel Trond H. Torsvik a;d, Rob Van der Voo b;*, Joseph G. Meert a;e, Jon Mosar a, Harald J. Walderhaug c a VISTA, c/o Geological Survey of Norway, Leiv Eiriksonsvei 39, N-7491 Trondheim, Norway b Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1063, USA c University of Bergen, Institute of Solid Earth Physics, Allegt. 41, N-5007Bergen, Norway d Institute for Petroleum Technology and Applied Geophysics, S.P. Andersens v. 15a, N-7491 Trondheim, NTNU, Norway e Department of Geography and Geology, Indiana State University, Terre Haute, IN 47809, USA Received 12 September 2000; received in revised form 16 February 2001; accepted 21 February 2001 Abstract Late Carboniferous^Early Tertiary apparent polar wander (APW) paths (300^40 Ma) for North America and Europe have been tested in various reconstructions. These paths demonstrate that the 500 fathom Bullard et al. fit is excellent from Late Carboniferous to Late Triassic times, but the continental configuration in northern Pangea changed systematically between the Late Triassic (ca. 214 Ma) and the Mid-Jurassic (ca. 170 Ma) due to pre-drift extension. Best fit North Atlantic reconstructions minimize differences in the Late Carboniferous^Early Jurassic and Late Cretaceous^ Tertiary segments of the APW paths, but an enigmatic difference exists in the paths for most of the Jurassic, whereas for the Early Cretaceous the data from Europe are nearly non-existent.
    [Show full text]
  • 38—GEOLOGIC AGE SYMBOL FONT (Stratagemage) REF NO STRATIGRAPHIC AGE SUBDIVISION TYPE AGE SYMBOL KEYBOARD POSITION for Stratagemage FONT
    Federal Geographic Data Committee U.S. Geological Survey Open-File Report 99–430 Public Review Draft - Digital Cartographic Standard for Geologic Map Symbolization PostScript Implementation (filename: of99-430_38-01.eps) 38—GEOLOGIC AGE SYMBOL FONT (StratagemAge) REF NO STRATIGRAPHIC AGE SUBDIVISION TYPE AGE SYMBOL KEYBOARD POSITION FOR StratagemAge FONT 38.1 Archean Eon A Not applicable (use Helvetica instead) 38.2 Cambrian Period _ (underscore = shift-hyphen) 38.3 Carboniferous Period C Not applicable (use Helvetica instead) 38.4 Cenozoic Era { (left curly bracket = shift-left square bracket) 38.5 Cretaceous Period K Not applicable (use Helvetica instead) 38.6 Devonian Period D Not applicable (use Helvetica instead) 38.7 Early Archean (3,800(?)–3,400 Ma) Era U Not applicable (use Helvetica instead) 38.8 Early Early Proterozoic (2,500–2,100 Ma) Era R (capital R = shift-r) 38.9 Early Middle Proterozoic (1,600–1,400 Ma) Era G (capital G = shift-g) 38.10 Early Proterozoic Era X Not applicable (use Helvetica instead) 38.11 Eocene Epoch # (pound sign = shift-3) 38.12 Holocene Epoch H Not applicable (use Helvetica instead) 38.13 Jurassic Period J Not applicable (use Helvetica instead) 38.14 Late Archean (3,000–2,500 Ma) Era W Not applicable (use Helvetica instead) 38.15 Late Early Proterozoic (1,800–1,600 Ma) Era I (capital I = shift-i) 38.16 Late Middle Proterozoic (1,200–900 Ma) Era E (capital E = shift-e) 38.17 Late Proterozoic Era Z Not applicable (use Helvetica instead) 38.18 Mesozoic Era } (right curly bracket = shift-right square bracket) 38.19 Middle Archean (3,400–3,000 Ma) Era V Not applicable (use Helvetica instead) 38.20 Middle Early Proterozoic (2,100–1,800 Ma) Era L (capital L = shift-l) 38.21 Middle Middle Proterozoic (1,400–1,200 Ma) Era F (capital F = shift-f) 38.22 Middle Proterozoic Era Y Not applicable (use Helvetica instead) A–38–1 Federal Geographic Data Committee U.S.
    [Show full text]
  • The Triassic Period and the Beginning of the Mesozoic Era
    Readings and Notes An Introduction to Earth Science 2016 The Triassic Period and the Beginning of the Mesozoic Era John J. Renton Thomas Repine Follow this and additional works at: https://researchrepository.wvu.edu/earthscience_readings Part of the Geology Commons C\.\- \~ THE TRIASSIC PERIOD and the BEGINNING OF THE MESOZOIC ERA Introduction to the Mesozoic Era: The Triassic Period is the first period of the Mesozoic Era, a span of time from 245 million years ago to 66 million years ago. Although the Mesozoic era commonly known as the "Age of the Dinosaurs", it should be pointed out that there were other important evolutionary developments taking place such as the appearance of the first mammal birds and flowering plans. The onset of the Mesozoic Era, the Triassic Period, was also a time of profound tectonic activity affecting the entire North American craton. In the east, the primary event was the breakup of Pangea and the formation of the Atlantic Ocean. In the west, it was the formation ofan Andean-type continental margin as the newly-formed continent of North America rapidly moved westward in response to the opening of the Atlantic Ocean coupled with the addition of exotic terranes to the western margin of the continent.. As the Atlantic oceanic ridge rose, the volume of ocean waters that was displaced was sufficient to result in the most extensive flooding of the continent by an epeiric sea since the Paleozoic; a sea whose presence was recorded by the accumulation of extensive carbonates throughout the continental interior. In the oceans, new life forms evolved to fill the vacancies brought about by the Permian extinction.
    [Show full text]