Monday December 3, 2012 (Discussion and Worksheet - Introduction to Continental Drift and Plate Tectonics)

In which rock layer would you not find dinosaur fossils? Why? The Launch Pad Monday, 12/3/12 In which rock layer would you not find dinosaur fossils? Why?

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Assignment Currently Open Summative or Formative? Date Issued Date Due Date Into GradeSpeed Final Day Quiz 11 S1 11/9 11/30 12/14 Quiz 12 S2 11/16 WS - The Phanerozoic Eon: The Mesozoic Era – The Age of Reptiles F6 11/28 12/7 WS - The Phanerozoic Eon: The Cenozoic Era – The Rise of Mammals and Flowering Plants F7 11/29 Quiz 13 S3

Recent Events in Science More Intense North Atlantic Tropical Storms Likely in the Future Read All About It! A study shows that tropical storms that make their way into the North Atlantic, and possibly strike the East Coast of the United States, likely will become more intense during the rest of this century. The study itself examines projected changes in the North Atlantic Power Dissipation Index (PDI) using output from 17 state-of-the-art global climate models and three different potential scenarios. The PDI is an index that integrates storm intensity, duration, and frequency. Researchers found that the PDI is projected to increase in the 21st century in response to both greenhouse gas increases and reductions in particulate pollution over the Atlantic over the current century. By relating these results to other findings in a paper we published May 13, 2012 in the journal Nature Climate Change, they found that, while the number of storms is not projected to increase, their intensity is. The results indicate that as more carbon dioxide is emitted, the stronger the storms get, while scenarios with the most aggressive carbon dioxide mitigation show the smallest increase in intensity, www.sciencedaily.com/releases/2012/11/1 21130151651.htm

Introduction to Plate Tectonics

Continental Drift - An Idea Before Its Time Antonio Snider-Pellegrini (no picture available) was a French geographer and scientist who first hypothesized the possibility of continental drift. In 1858, Snider-Pellegrini published his book, "The Creation and its Mysteries Unveiled“, in which he proposed that all of the continents were once connected together during the Pennsylvanian Period. He based this theory on the fact that he had found plant fossils in both Europe and the United States that were identical. He found matching fossils on all of the continents.

Continental Drift - An Idea Before Its Time 57 years later, German scientist Alfred Wegener proposed his continental drift hypothesis (1915.) His work was published as “The Origin of Continents and Oceans.” The continental drift hypothesis states that a supercontinent called Pangaea began breaking apart about 200 million years ago. The continents “drifted” to their present positions.

Pangaea approximately 200 million years ago Figure 7.2

Continental Drift - An Idea Before Its Time Evidence Cited by Wegener Wegener noted the obvious fit of South America and Africa.

Continental Drift - An Idea Before Its Time Evidence Cited by Wegener He pointed out that fossils match across the seas.

Continental Drift - An Idea Before Its Time Evidence Cited by Wegener He pointed out that fossils match across the seas.

Continental Drift - An Idea Before Its Time Evidence Cited by Wegener He pointed out that fossils match across the seas.

Continental Drift - An Idea Before Its Time Evidence Cited by Wegener Wegener also discovered that rock types and structures match the seas.

Continental Drift - An Idea Before Its Time Evidence Cited by Wegener There are similar mountain ranges on different continents.

Continental Drift - An Idea Before Its Time Evidence Cited by Wegener He noted that ancient climate evidence matches on the present-day continents.

Continental Drift - An Idea Before Its Time The main objection to Wegener’s proposal was the inability to find a mechanism for continental drift.

The Continental Drift Mechanism Discovered: Plate Tectonics Plate tectonics is the theory that describes the large-scale motions of Earth's lithosphere. The model builds on the concepts of continental drift, developed by Wegener during the first decades of the 20th century. It was accepted by the geoscientific community after the concepts of seafloor spreading were developed in the late 1950s and early 1960s.

The Continental Drift Mechanism Discovered: Plate Tectonics The concept of plate tectonics is more encompassing than the idea of continental drift. Plate tectonics is associated with Earth’s rigid outer shell, called the lithosphere. Earth’s lithosphere consists of several “plates”, which are moving very slowly across the mobile asthenosphere below. The largest of these plates is the Pacific plate. The plates are mostly beneath the ocean.

Figure 1.18 (left)

Figure 1.18 (right)

New crust is created at mid-oceanic ridges. The Earth’s lithosphere is divided into plates, which move on top of the asthenosphere.

Plates move apart (diverge) and crash together (converge.) Plate tectonics, the mechanism for continental drift, is caused by convection in the asthenosphere causing an upwelling through the lithosphere.

Plate Tectonics The Earth’s asthenosphere lies just beneath the lithosphere. The asthenosphere is hotter and weaker than the lithosphere. This allows for the motion of the lithosphere over the asthenosphere

All major interactions among plates occur along their boundaries. Plate Tectonics All major interactions among plates occur along their boundaries.

Worksheet Introduction to Continental Drift and Plate Tectonics Reference notes on teacher website dated Monday, 12/3/12.