Blog #4

The effects of global warming have had devastating effects on the coral reefs found in the Belize Barrier Reef, where the Great Blue Hole is found.  Increased water temperatures due to the El Nino effect have caused a large portion of the coral in the reef to bleach and die.  The death of the coral also means the death of the algae that is essential to the health of the coral reef ecosystem.  No algae means less photosynthesis, which means less absorption of carbon dioxide and lower oxygen levels in the water.  This interrupts the balance of the atmospheric gases that help make up the composition of seawater, which can result in the degradation of the habitat of the organisms that inhabit the region.  

Dead Staghorn Corals in Belize's Barrier Reef

 

  A main contributor to global warming is human activity.  Humans need to reduce pollution and the emission of greenhouse gases, coastal development and over-fishing, which all have an impact on the ecosystem of the region.  If humans continue to have such a negative impact on the environment, ecosystems like those present in the Great Blue Hole are at risk of habitat degradation.

 

Sources:

http://news.bbc.co.uk/2/hi/science/nature/735941.stm

http://news.nationalgeographic.com/news/2003/03/0325_030325_belizereefs.html

http://www.culturecuts.net/shortlist/ccsfeature/ccsf8_cp.html

http://www.nasa.gov/vision/earth/everydaylife/climate_class.html

 

Blog#3

     The Earth’s wind patterns have an effect on the soil composition at the bottom of the Great Blue Hole.  The low humidity of the continental tropical air mass of North Africa is due to the lack of water and the subsidence of the subtropical high.  As the air subsides toward the Earth’s surface, it moves outward away from the center of the subtropical high.  The resulting wind pattern from North Africa is known as the northeast trade winds.  These winds, and the resulting ocean currents, may be responsible for transporting small particles from the African continent to the Caribbean.  When the dry northeasterly trade winds meet the humid maritime tropical air mass, any particles in the air are precipitated onto the land/oceans. The solvent properties of water allow it to transport these particles and nutrients that may be present.  This may explain the presence of what geologists believe to be African dust flux that was found in a core sample of the soil at the bottom of the Great Blue Hole.

Global pattern of wind and pressure

 

 

 

 

 

 

Sources:

http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/weather_systems/air_masses_types.html

http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/circulation/global_scale_circulation.html

http://soundwaves.usgs.gov/2001/06/

 

Blog#1

Map of Belize

Great Blue Hole, Lighthouse Reef Atoll, Belize (Photographed by David Doubilet, National Geographic)

Believed to be the largest feature of its kind in the world, the Great Blue Hole is located in Belize’s Lighthouse Reef Atoll, a large coral reef, or biologic sedimentary rock formed by the accumulation of organic material (i.e., coral).  The bedrock in the region is limestone, a chemical sedimentary rock formed by calcite.  The Great Blue Hole is a giant sea-hole, or a sinkhole found in the ocean, measuring 984 feet in diameter and 407 feet deep.  The interesting feature of this site is an underwater cave.  

Stalactites, Half Moon CayeGreat Blue Hole, Lighthouse Reef Atoll, Belize

 

The presence of stalactites, stalagmites and columns shows the cave was once above sea level.  As sea levels rose, the caverns grew, and the roof weakened and collapsed, forming the sinkhole.  At some point, Lighthouse Reef Atoll experienced some tectonic movement along the continental/oceanic transform fault, as the North American Plate and Caribbean Plate moved against each other, and shifted at an angle of approximately 12 degrees, shown by the angle of the stalactites found in the sea cave, which only form in a perpendicular pattern due to gravity.  

 Sources:

http://ga.water.usgs.gov/edu/earthgwsinkholes.html

http://www.physicalgeography.net/physgeoglos/s.html

http://ambergriscaye.com/pages/town/blueholebottom.html

http://geology.com/nasa/great-blue-hole/

http://photography.nationalgeographic.com/photography/photos/pod-best-of-2007/blue-hole-belize-reef_pod_image.html

http://soundwaves.usgs.gov/2001/06/

http://ga.water.usgs.gov/edu/earthgwsinkholes.html

http://www.ecophotoexplorers.com/images/belizemap.gif

http://monkeybusinesstours.com/diving-blue-hole-half-moon-caye-lighthouse-reef-full-day

http://en.wikipedia.org/wiki/File:Tectonic_plates_boundaries_detailed-en.svg

http://en.wikipedia.org/wiki/Great_Blue_Hole

 

Blog#2

The Great Blue Hole is a sinkhole that was caused by the weathering of limestone dissolved by subsurface drainage.  The rock found in the cave of the Great Blue Hole is limestone karst.  It is believed that at the end of the Great Ice Age, as glaciers melted, sea levels rose, forcing more groundwater through the open spaces in the limestone karst.  As the rock dissolved, caverns developed underground.  The stalactites, stalagmites and columns were formed by calcite deposits from the chemical dissolution of the limestone.  

Illustration of how Caves/Caverns form

Illustration of how Sinkhole forms

 

The depth and isolation of the sea floor at the bottom of the Great Blue Hole has resulted in an interesting soil profile.  In 1997, divers took core samples from the bottom of the Great Blue Hole.  The 2-foot long core samples showed a long history of sedimentary layers. There is no oxygen near the bottom of the hole, and high levels of hydrogen sulfide prevent bottom dwellers from disturbing the sediment.  The samples showed layers of atmospheric fallout such as pollen, spores, as well as mercury, and arsenic.  The clay-rich sedimentary layers resulted in a gleization process, reducing the porosity of the soil, which caused the slow deposition and accumulation of organic material.  

Diver exploring the reef in the Great Blue Hole, approx. 60-80 feet underwater

 

Sources:

http://soundwaves.usgs.gov/2001/06/

http://www.news-world.us/pics/tag/coral-reef/

http://virtual.yosemite.cc.ca.us/chudelson/online/soils.htm

http://www.tulane.edu/~sanelson/geol111/groundwater.htm

intro

When I was searching for a site to use for this course, I wanted something interesting that I had never seen or studied before.  I chose this site because it is a very interesting geological phenomenon called a sinkhole, but since it is in the ocean, it is referred to as a sea-hole.  It is believed to be the deepest sea-hole in the world, and it is an underwater cave with huge stalactites and other interesting geological forms.  I am confident that there are enough geographical forms/processes present to satisfy the requirements of this assignment.  I am very interested in learning more about the Great Blue Hole in Belize. 

Ahmed ALHijji