WEEKLY OCEAN NEWS

DATASTREME OCEAN WEEK FOUR: 27 September to 1 October 2004

• The travels of Hurricane Jeanne -
• Jeanne traveled across Florida on Sunday after making landfall along Florida's Atlantic coast near Vero Beach late Saturday night as a Category 3 on the Saffir-Simpson Hurricane Intensity Scale. As it moved across the Florida Peninsula on Sunday, Jeanne weakened to a marginal hurricane, but still was accompanied by strong winds and locally heavy rain. More than one million customers were without electric power. [CNN]
• Jeanne swept across the Bahamas on Friday and early Saturday with winds of up to 100 mph and torrential rains. [CNN]
• While moving along the northern coast of Hispaniola as a tropical storm, Jeanne left a trail of destruction due to the heavy rains and resulting mudslides. As many as 1500 people died in Haiti, where civil unrest has arisen during this past week despite humanitarian relief efforts. [CNN]
• Inspecting the eyewall of Hurricane Jeanne-- A portfolio of pictures taken of the clouds that formed the eyewall of Jeanne was posted by NOAA scientists. These photos were taken by from NOAA hurricane hunter aircraft that penetrated the eye of Hurricane Jeanne last week when the hurricane was over the western Atlantic. [NOAA News]
• An aerial view of Ivan's destruction --Last week NOAA posted more than 1300 aerial images of the destruction caused by Hurricane Ivan over the previous weekend when the hurricane made its first landfall along the Gulf Coast near Mobile Bay. [NOAA News]
• Mapping coastlines by satellite -- The European Space Agency has been collecting data on the coastlines from its satellites as part of a new program called COASTCHART. These data are to be used for improved hydrographic mapping. [ESA]
• A "Big One" could generate a tsunami in Southern California -- Researchers at the University of Southern California report that a strong earthquake (magnitude of 7.6 or greater) under Santa Catalina Island off the California coast could generate a significant tsunami that would travel across San Pedro Bay and devastate the Los Angeles and Long Beach Harbors. [University of Southern California]
• Newly discovered hydrothermal vents located in the South Pacific -- A team of marine scientists headed by a biology professor from Penn State University reported discovering a cluster of hydrothermal vents on the seafloor more than a mile below the ocean surface in the Lau Basin of the South Pacific. [Penn State University]
• New structure within the West Antarctic ice sheet found -- A group of British and US scientists recently reported finding a huge fold in the ice of the West Antarctic ice sheet using radar, suggesting a relatively rapid flow of the ice sheet. They believe that their discovery means that the ice sheet is more susceptible to change than previously thought and could potentially cause a rise in sea level over the next several centuries. [EurekAlert!]
• A long-neck sea predator discovered-- Chinese scientists reported the discovery of the discovery of the skeletal remains that appear to be a long-necked sea reptile, which had preyed on marine life in the shallow seas covering southeast China more than 230 million years ago. [EurekAlert!]
• A new Alaskan marine habitat discovered -- Using scuba-gear and an Alaskan fishing boat, researchers at the University of Alaska-Fairbanks discovered a bed of rhodoliths, or colorful marine algae resembling coral, in Prince William Sound. Rhodoliths had not been previously found along the coastal waters of Alaska. [SitNews]
• Coral reefs in the Caribbean threatened -- The World Resources Institute recently reported that a study indicates that approximately two-thirds of the coral reefs in the Caribbean are now threatened by a variety of pressures associated with human activity, to include overfishing and pollution. This environmental research group recommends better protection efforts be instituted. [ENN]
• Canadian coastal cities cited as major sewage polluters -- The Sierra Legal Defense Fund recently reported that at least one-half dozen coastal cities in Canada continue to dispense millions of gallons of nearly untreated sewage into surrounding waters. [US Water News Online]
• Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Variations in Marine Sediment Thickness

Sediments are particles of organic or inorganic origin that accumulate in loose form in depositional environments such as lake or ocean bottoms. Marine sediments, the central focus of this week's investigations, have a variety of sources and exhibit a wide range of composition, size, and shape. Marine sediments settle to the ocean floor as unconsolidated accumulations but ultimately may be converted to solid sedimentary rock via compaction and cementation. The pattern of variations in marine sediment thickness on the ocean floor confirms some basic understandings regarding marine geological processes.

Go to the DataStreme Ocean homepage and under "Geological," click on "Sediment Thickness." This map of marine sediment thickness in the ocean basins was compiled by the National Geophysical Data Center (NGDC), Marine Geology and Geophysics Division primarily based on existing maps, ocean drilling, and seismic reflection profiles. Sediment thickness is color-coded in meters from violet (thinnest) to red (thickest). Many factors account for the variation in the thickness of marine sediment deposits including type and location of sediment sources, sediment transport mechanisms, and the age of the underlying crust.

According to the map, sediment thickness generally increases with distance from near the central portion of an ocean basin to the continental margin. This pattern may be explained by the principal sediment source and/or the age of the underlying crust. Rivers and streams that empty into the ocean slow and diverge releasing the bulk of their suspended sediment load in coastal environments (e.g., bays, estuaries, deltas) and onto the continental shelf. Ocean currents transport sediment along the coast. In some areas of the continental shelf, massive amounts of sediment accumulate, become unstable, and flow down the continental slope to the base of the continental rise and beyond. However, only the finer fraction of river-borne sediment is swept into the deep ocean waters. Thickening of marine sediments in the direction of the continental margin may also reflect the aging of oceanic crust with distance away from divergent (spreading) plate boundaries where new oceanic crust forms. The older the crust the longer is the period that sediment rains down on the ocean bottom and the thicker is the blanket of accumulated sediment.

The map indicates that the thickness of marine sediment deposits is greater in the continental margin along the Atlantic coast of North America than along the Pacific coast. The Atlantic coast of North America is a passive margin; that is, the continental margin is not affected significantly by tectonic processes (no plate boundary) and the principal geological processes consist of sedimentation along with erosion by ocean waves and currents. In fact, passive margins and relatively thick marine sediment deposits occur on both sides of the Atlantic. (Passive margins also occur around the Arctic Ocean and surrounding Antarctica.) On the other hand, the Pacific coast of North America is an active margin; that is, the continental margin is associated with plate boundaries and is subject to deformation by tectonic stresses. Active continental margins are relatively narrow so that sediment delivered to the coast by rivers and streams flows directly into deeper water or trenches--preventing thick accumulations of marine sediments in the continental margin.

1. The thickness of marine sediment deposits is greater in the[(continental margins)(deep-ocean basins)].
2. The thickness of marine sediment deposits generally is greater in[(active)(passive)] continental margins.

• 27 September 1854... After colliding with the French ship SS Vesta in dense fog, the American Collins Line steamship Arctic sank with more than 300 people on board near Cape Race, Newfoundland, marking the first great disaster in the Atlantic Ocean. (Wikipedia)
• 27 September 1922...Report on observations of experiments with short wave radio at the Naval Aircraft Radio Laboratory in Anacostia, DC started US Navy development of radar. (Navy Historical Center)
• 27 September 1958...A typhoon caused the death of nearly 5000 people on Honshu, the main Japanese island. (Wikipedia)
• 28 September 1542...Portuguese explorer Juan Rodríguez Cabrillo sailed into present-day San Diego (CA) Bay during the course of his explorations of the northwest shores of Mexico on behalf of Spain. His landing at Point Loma Head apparently was the first known European encounter with California. Before dying on the Channel Islands off the Santa Barbara coast in January 1543, he had explored much of the California coast. (The History Channel)
• 28 September 1850...An Act of Congress (9 Stat. L., 500, 504) provided for a systematic coloring and numbering of all buoys for, prior to this time, they had been painted red, white, or black, without any special system. The act "prescribed that buoys should be colored and numbered so that in entering from seaward red buoys with even numbers should be on the starboard or right hand; black buoys with odd numbers on the port or left hand; buoys with red and black horizontal stripes should indicate shoals with channel on either side; and buoys in channel ways should be colored with black and white perpendicular stripes." (US Coast Guard Historians Office)
• 29 September 1959...Hurricane Gracie made landfall near Beaufort, SC with sustained winds of 97 mph and a peak gust of 138 mph. Ten people were killed in South Carolina and Georgia. As the weakening storm moved through Virginia on the 30th, she spawned an F3 tornado at Ivy, VA, which killed 11 people. On the same day, a storm produced 28 inches of snow at Colorado Springs, CO. (David Ludlum)
• 30 September 1932...Tropical cyclone rainfall of 4.38 inches at Tehachapi in southern California over 7 hours caused flash floods on Auga Caliente and Tehachapi Creeks resulting in 15 deaths. (The Weather Doctor)
• 30 September 1954...The USS Nautilus, the world's first nuclear-powered submarine, is commissioned by the U.S. Navy. In addition to breaking numerous submarine travel records to that time, the Nautilus made the first voyage under the Arctic sea ice at the geographic North Pole in August 1958, passing from the Pacific to Atlantic Ocean basins. The Nautilus was decommissioned on 3 March 1980 and is currently on display at the Submarine Force Museum in Groton, CT. (The History Channel)
• 30 September 1997...Omega Navigation Station Hawaii ceased operation, coinciding with the end of worldwide Omega transmissions. (USCG Historian's Office)
• 1 October 1844...U.S. Naval Observatory headed by LT Matthew Fontaine Maury occupied its first permanent quarters. (Naval Historical Center)
• 1 October 1846... The British naturalist Charles Darwin, ten years after his voyage on the Beagle, began his study of barnacles, which was to appear in four volumes on living and fossil Cirripedes (barnacles). For his observations, he had a single lens microscope made to his own design. (Today in Science)
• 1 October 1976...Hurricane Liza brought heavy rains and winds to Brazos Santiago, Mexico, causing a dam to break on the Cajoncito River, which killed 630 people as a wall of water crashed into the town of La Paz. (The Weather Doctor)
• 1 October 1893...The second great hurricane of the 1893 season hit the Mississippi Delta Region drowning more than 1000 persons. (David Ludlum)
• 2 October 1836...The British naturalist Charles Darwin returned to Falmouth, England, aboard the HMS Beagle, ending a five-year surveying expedition of the southern Atlantic and Pacific oceans, that included visits to Brazil, the Galapagos Islands, and New Zealand. The information and experience obtained from this voyage led Darwin to develop his historic work on the theory of evolution with the 1859 work entitled, The Origin of Species by Means of Natural Selection. (The History Channel)
• 2 October 1867...A hurricane struck Galveston, TX with a storm tide that produced $1 million damage. (Intellicast)
• 2 October 1882...A major hurricane struck the Louisiana Delta with 100-mph winds and 12-ft storm tide which inundated the bayous resulting in 1500 deaths. (Intellicast)
• 2 October 1898...A hurricane struck the Weather Bureau (now National Weather Service) hurricane observation post at Carolina Beach, North Carolina and swept away the office's outhouse. The storm became known as the "Privy Hurricane". (Northern Indiana NWSFO)
• 3 October 1841...The "October Gale," the worst of record for Nantucket, MA, caught the Cape Cod fishing fleet at sea. Forty ships were driven ashore on Cape Cod, and 57 men perished from the town of Truro alone. Heavy snow fell inland, with 18 inches near Middletown, CT and 3 inches at Concord, MA. (David Ludlum)

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Prepared by AMS DSOcean Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2004, The American Meteorological Society.