Spencer Cody: Of Geology, Time, and Ice, June 2, 2016

NOAA Teacher at Sea
Spencer Cody
Onboard the NOAA Ship Fairweather
May 29 – June 17, 2016

Mission:  Hydrographic Survey
Geographical Area of the Cruise:  along the coast of Alaska
Date: June 2, 2016
Observational Data:
Latitude:  58˚ 17.882′ N
Longitude:  134˚ 24.759′ W

Weather Data from the Bridge:  
Air Temp: 16˚C (61˚F)
Water Temp: 8.9˚C (48˚F)
Ocean Depth:  9.7 m (31.8 ft. at low tide)
Relative Humidity:  56%
Wind Speed:  18 kts (21 mph)
Barometer:  1,006 hPa (1,006 mbar)

 

Science and Technology Log: After a full day of flying, I arrived in Juneau, Alaska, on Sunday.  The Fairweather came into dock early the next morning to host a very special occasion for friends, family, and the public.  It was a Dependents Day Cruise to go with the Memorial Day celebration.  It was an opportunity for those

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The NOAA Ship Fairweather in the bottom center docked in Juneau, Alaska, preparing for her next hydrographic leg.

who work onboard the Fairweather to show others outside of NOAA what they do while the crew, friends, family, and guests sailed onboard to the Taku glacier in Taku Inlet and back to dock in Juneau.  The day was filled with demonstrations on what the crew does in order to complete their missions and the significance of having a ship such as the Fairweather fulfill its assigned tasks.  We were split up into multiple groups in order to cover the basics of ship operations and the science and research carried out by the crew.  Guests were treated to demonstrations of bridge operations, hydrographic survey techniques and equipment, dive operations and control station demonstrations.  One highlight of the many demonstrations that were carried out

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The crew demonstrate a launch and retrieval of one of the hydrographic survey launches.  The Fairweather has four of these 28′ boats including three additional boats for fast rescue and utility purposes.

was the showing of how the launch boats are lowered into the water and then retrieved.  The Fairweather was maneuvered in such a way that the launch boat was provided a small patch of sea that was calm, a “duck pond,” by blocking the oncoming waves for the launch boat.  While this was not necessary for the weather that day, it did drive home the point about the many ingenious methods that must be employed in carrying out day-to-day operations on a vessel like the Fairweather.  By the time these demonstrations and tours were concluded, we had arrived at the Taku Inlet to see the Taku glacier.

Seeing something that is massive enough to carve solid rock such as the Taku glacier was awe inspiring.  This brings us to one of the key reasons for the complexity of the local geology and the sea channels that the Fairweather will be mapping on the next leg.  After periods of uplift and mountain building, the terrain was recently sculpted with rivers of ice flowing outward to lower sea levels from the ice fields above.  Glaciers encapsulated much of Southeastern Alaska up until the Wisconsin glaciation came to an end about 14,000 years ago.  During this same time, the Laurentide continental glacier still covered much of East River South Dakota.  As the glaciers receded, the ocean levels rose to accommodate the global deluge of melt water.  What was once

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The Taku glacier at the end of Taku Inlet displays the forces of erosion at a remarkable scale.

glaciated land is now well below sea level.  Since glaciers have a remarkable power of erosion, U-shaped valleys have been carved throughout this region.  Where these valleys dip below sea level, they frequently end up becoming important bays or passageways for commercial and private traffic.  Glaciation has also given these passageways some unique characteristics that makes having reliable navigation mapping critical.  Many of the navigable passageways in Southeastern Alaska are your characteristic fjords.  They have been carved deeply by the weight of hundreds or even thousands of feet of ice; yet, they are usually narrow with valley walls that run vertically straight into the air.  This topography largely continues below sea level meaning that in many locations the passageways, straits, and canals formed by glacial action can quickly deviate from hundreds of feet deep to shoals in a matter of very short distances.  The complexity and potential hazards of these fjords is enhanced through the process of glacial isostatic adjustment when the earth shifts back upward after the massive weight of a glacier subsides.  Take these relatively recent geological and climatological

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Much of the rock of the area shows obvious signs of glacial action scouring across the landscape such as this rock near the Mendenhall glacier outside of Juneau.

processes and apply them to the complex system of islands of the Alexander Archipelago that was formed through shifting transform boundaries between the North American and Pacific plates.  Now one can start to appreciate the degree to which timely mapping is needed for this part of the world requiring precision and accuracy in order to provide nautical charts that cater to the needs of growing commercial and private interests in the area.

 

Personal Log:

Dear Mr. Cody,

We boarded our ship in San Francisco and cruised under the Golden Gate Bridge passing by Alcatraz Island.  At sea I had the chance to tour the ship.  It is huge!  It holds 1,800 passengers and has a crew of 932.  I am still learning how to get around the ship.  It is like a little city on the ocean.  (Dillion is one of my science students who went on an Alaska cruise with his family in May and will be corresponding with me about his experiences as I blog about my experiences on the Fairweather.)

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Dillion finally at sea en route to his first stop in Alaska.

Dear Dillion,

I boarded the Fairweather the day after I arrived in Juneau.  I, too, am still learning my way around the ship and learning the names of the crew.  Everyone on the crew has been very helpful in helping me find my way around the ship and learning about what they do to make the Fairweather’s mission successful.  The Fairweather is designed to hold more than 50 crew members consisting of NOAA Corps officers, engineers, deck, survey, stewards, and electronic technicians.  While your cruise ship is built for comfort for vacationers, the Fairweather is built for utility and efficiency in accomplishing a wide range of tasks.  Though the Fairweather’s primary role is to carry out hydrographic mapping of the sea floor in order to provide reliable navigation charts and increase our understanding of the ocean floor, the ship’s crew has been involved in numerous other projects in just the last year including launching wave and weather monitoring buoys, contributing data to surveys tracking changing climate in the Arctic, participating in marine

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Unpacking and settling into my stateroom aboard the Fairweather.

mammal observations and new marine mammal survey techniques, carrying out phytoplankton tows, aiding the Navy in glider development, mapping nautical obstructions, and retrieving climate and ocean sensors.

 

Did You Know?

The Fairweather was launched in 1967 and named after Mount Fairweather in Alaska.  She was constructed along with two other sister ships, the Rainier, in service, and the Mount Mitchell, retired from NOAA service.  All three ships were named after tall mountains in the United States.

Can You Guess What This Is?

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A. a vent   B. a speaking tube   C. a horn   D. a periscope

The answer will be provided in the next post!