American, BIO 240

Excerpt: ... entific community Growing Weight of Evidence post WWII interest in oceans detailed map of ocean floor developed series of mid-ocean ridges (Fig 3.6, p43-43) > sites of underwater volcanoes sites where new oceanic crust is formed > proposed by Harry Hess (Princeton) 1960s > see Figure 3.7 (p44) oceanic lithosphere slips away from site of ridge = seafloor spreading centers descending older crust at subduction zones Evidence of Crustal Motion zone of earthquakes correspond with spreading centers and subduction zones (Fig 3.8, p 45) temperature of mantle hottest near ridges > correspond to idea of convection cells age of the oceanic crust <180 million years > about 1 million years old near ridge > thickness of ocean sediment increase away from ridge Magnetic Patterns in Ocean Floor s earth has magnetic poles (N and S) > makes use of compass possible evidence suggests that N and S magnetic poles have revered about 170 times > may be due to changes in the earths ...

Rutgers, GEO 101

Excerpt: ... Lecture 14 (March 28) Chapter 13: Introduction to Landform Study The Composition of Earth Igneous Rocks Sedimentary Rocks Metamorphic Rocks The Rock Cycle Continental and Ocean Floor Rocks Isostasy The Study of Landforms Some Critical Concepts Internal and External Geomorphic Processes Uniformitarianism Geologic Time Scale and Pattern The Composition of Earth (p. 389) How is a mineral different from a rock? Describe the general differences among igneous, sedimentary, and metamorphic rocks. The Study of Landforms (p. 401) Briefly define the terms topography, landform, and geomorphology. Some Critical Concepts (p. 403) Contrast the concepts of "internal" and "external" geomorphic processes. How does the doctrine of uniformitarianism help us understand the history of Earth? What is generally meant by the term geologic time? What is the importance of geologic time to the doctrine of uniformitarianism? Scale and Pattern (p. 405) In the study of geomorphology, why do we primarily con ...

Wisc Stevens Point, ADAVE 584

Excerpt: ... What is under the sea? What would the oceans look like if there was no water? Valleys? Plains? Mountains? Volcanoes? All of the above! The ocean floor is made up of many landforms! What the Ocean Floor Looks Like. The Deep Ocean Basin Is 2.5 to 3.5 miles deep Covers 30 % of Earth's surface Has features such as abyssal plains, deep-sea trenches and seamounts. The Abyssal Plain The abyssal plain is flat, in fact it is the flattest place on the earth! It is flat like the plains in the United States because a thick layer of sediment covers the hills and valleys below it which create a blanket smoothing the topography. DeepSea Trenches Deep-sea trenches are the deepest parts of the ocean. The Marianas Trench Pacific Ocean, More than 35,000 feet (about 6.6 miles) deep! Continental Shelf Are the shallowest part of the ocean's floor. About 650 feet deep. Ends at the continental slope, which leads to the deepest parts of the ocean. The Continental Slope Connects the Continental Shelf and the Oc ...

University of Hawaii - Hilo, OCN 621

Excerpt: ... thic energy sources a) Coastal benthos i. Sources of organic carbon - in situ primary production - detritus ii. Detrital utilization c) Deep-sea benthos i. Sources of organic carbon ii. Deep-sea carbon budget _ Definitions: Benthos - organisms living on or in the ocean floor . Benthic ecology - study of the structure and dynamics of organisms living on or in the ocean floor , and the interactions of these organisms (at individual, population and community levels) among themselves and with their environment. Why study benthos and benthic ecology? Gage and Tyler, 1992 Most phyla are found in marine sediments Dunn et al., 2008: Nature, 4/14/2008 CT scan of subtidal Narragansett Bay sediments with large cerianthid anemone tube (Ceriatheopsis americanus), several small clams, and numerous polychaete tubes (http:/www.epa.gov/a ed/html/ct/index.html, and Perez et al., 1999) ...

Washington University in St. Louis, EPSC 108

Excerpt: ... (inclination) Latitude Apparent polar wandering THE EARTH HAS A STRONG, BUT VARIABLE, MAGNETIC FIELD The Earth's magnetic field REVERSES itself, irregularly. Known from PALEOMAGNETISM IN VOLCANIC FLOWS WHERE WAS THE ANCIENT NORTH POLE ? FURTHER EVIDENCE FOR TECTONIC PLATE MOTION SINCE THE POLE DIRECTION ALIGNS IF THE CONTINENTS DRIFTED Figure 3-37 MOTIONS OF CONTINENTS MAY BE MEASURED FROM SPACE AND BY LASERS ON LAND. THE RATES OF MOTION DIFFER FROM PLACE TO PLACE AND THE DIRECTIONS VARY. Sea floor spreading, a related topic Henry Hess (1960) Bathymetry of seafloor Located mid-ocean ridge and deep ocean trenches Found that ocean crust is created at midocean ridges And, ocean crust is destroyed at ocean trenchs EARTH'S VARIABLE MAGNETIC FIELD IS RECORDED ON THE OCEAN FLOOR Vine and Matthews (1963) Magnetic stripes represent changes in Earth's magnetic field Polarity reversals Symmetric pattern caused by spreading at midocean ridge Rates of spreading Faster spreading ra ...

East Los Angeles College, PX 266

Excerpt: ... PX266 Geophysics (2008/09) Lecture 14 Handout Mid-ocean Ridges Dr. Gavin Bell Age of ocean floor Colour scale represents ocean floor age based on radiometric dating. Very oldest oceanic plate material is around 200Ma due to continual subduction. Clear pattern in age of ocean floor : youngest material by mid-ocean spreading ridges where magma upwells and cools to form basalt. The mid-Atlantic ridge is very obvious and was originally responsible for the break-up of Pangea (Jurassic north Atlantic opens up; later in the Cretaceous, the south Atlantic opens). Paleomagnetism and sea-floor spreading Magnetic polarity can be measured by ship-towed magnetometer. "Stripes" of width x v0 treversal 2 observed parallel to spreading ridges. The reversal chronology can be verified by radiometrically dating oceanic basalts (e.g. by potassium-argon isochron method). Topography of mid-ocean ridges Figure adapted from Fowler. Typical ridge structure: gentle rise up towards ridge axis with deep trench at the axis. T ...

UWO, INSTRUCT 1022

Excerpt: ... Earth Sciences 1022/2281b Lecture Brief 24 Feb 09 THE OCEAN FLOOR Mapping the ocean floor is done by comparing multibeam sonar and satellite images Continental Margins: passive continental margins not associated with plate boundaries, volcanoes, or earthquakes; three parts include: continental shelf: gentle slope from shoreline to 130 m depth, averages 80 km wide; valuable for oil and gas reserves, sand and gravel deposits, and fishing grounds - rivers cut into it during glaciations when sea level fell and mammals roamed on it continental slope: steeper slope beyond the shelf about 20 km wide that forms the boundary between continental crust and oceanic crust continental rise: gentle slope formed by turbidity currents and deep-sea fans submarine canyons and turbidity currents: valleys cut into the continental slope - some extend from river valleys carved during glaciations, others form by earthquake induced turbidity currents of dense sediment-rich water eroding the shelf and slope - turbidity currents fo ...

Cal. Lutheran, ASSI 03

Excerpt: ... Evidence for Plate Tectonics Example Power Point Earth Science Standard: Dynamic Earth Processes Students know features of the ocean floor (magnetic patterns, age, and sea-floor topography) provide evidence of plate tectonics Transform faults: faults that run across a mid-ocean ridge Mid-ocean ridges: undersea mountain chain where new ocean floor is produced: a constructive (divergent) plate boundary Vocabulary Mid-ocean ridge Ocean-floor spreading: process in Vocabulary which old ocean floor is pushed away from a mid-ocean ridge by the formation of new ocean floor Trenches: V-shaped valley on the ocean floor where old ocean floor is subducted; a convergent plate boundary Ocean Floor spreading Volcanic and earthquake activity occurs at the mid-ocean ridges. As lava erupts and hardens, ocean floor moves away on either side of the ridge Deepest Parts of the Oceans As older ocean floor moves away from midocean ridges, it moves down deep into Earth along trenches. Trenches are fou ...

Colorado State, GEOL 120

Excerpt: ... Northern lights are more frequent around the magnetic pole We can learn three things from Paleomagnetism: 1) Direction to the magnetic pole 2) Distance to the magnetic pole (magnetic inclination, like a dip needle) gives paleolatitude 3) Polarity (normal or reversed) * If we know the age of the rock, then we know when these things are true. APW Apparent Polar Wander Evidence from ocean floor s - Long assumed ocean floor s were old, flat, or `dead' - Actually: 1) Crust everywhere < 200 Ma years old 2) Generally `thin' sediment cover 3) Ocean bottom is rough: with canyons, seamounts, etc. - All the ocean's floor is youngest in the middle, gets older toward the continents - Mid Ocean Ridge (M.O.R.'s) 1) Mountain chains ~ 70,000 Km long 2) In some places, they're center of the oceans (thus, mid ocean) 3) Narrow depression at crust 4) Young. volcanism, pillows, earthquakes, hot water Magnetic Strips - Studies of magnetic properties of the seafloor revealed bands of alternating `normal' and `reversed' magnet ...

Wisc Stevens Point, CBODA 844

Excerpt: ... Unit Plan Lesson 7: Sunken Treasures Social Studies, Language Arts Grade: 3 Rationale: It is important that students understand what humans have left on the ocean floor , and how those items got there. Many times students learn that there are items on the ocean floor , but do not understand why. This is an opportunity for students to find out how history could have played a role in those items getting to the bottom of the ocean. Science Standards Included: B.4.1 Identify and examine various sources of information that are used for constructing an understanding of the past, such as artifacts, documents, letters, diaries, maps, textbooks, photos, paintings, architecture, oral presentations, graphs, and charts. B.4.7 Identify and describe important events and famous people in Wisconsin and United States history. Objectives/Intended Learning Outcomes/Goals: 1. Students will be able to write a story showing how a given treasure that is hidden at the bottom of the ocean is linked to a given person in history. 2. Stud ...