Field Trip Post: Number Four

See if you can guess which coast is in each clip. Fun fact: Most of the advertisements and promotional materials feature the Northern Coast and West End Bay

One of the many benefits of Roatán for divers is the fact that it has two vastly different coasts. The Northern coast, which borders the Caribbean Sea, has a very gentle slant into the ocean and has more depositional landforms. The Southern Coast is mainly known for its tall walls that drop off into the abyss.

A view of the Southern Coast from my plane

The Northern Coast

Waves gradually carry in material from the ocean and deposit it. There are various reefs and spilling breakers which cause water to flow differently and reach certain parts of the island at different frequencies and intensities.

In the above image, forms are marked in red.

The tombolo has been formed by receding waves that pull material (such as sand and soil) away from the beach. The beaches have been created by incoming waves. Tidal inlets are present because of water runoff from the island itself and receding waves. Sand has been deposited on the reefs because the receding waves which has allowed the sand to migrate.

The Southern Coast

My buddy at Mary's Place

Most erosional landforms occur on the Southern Coast, yet have been covered by sea level rise. Caves, notches and arches occur at depths of around 40 - 90ft. The below image shows a notch that has been carved by the waves which have eroded away the rock.

One of the few above-sea level South end notches. The beach, shown above, is quite possibly a man-made feature because it is on the South side of the island. Walls, drop-offs and very steep surging breakers are more common. These features help create pristine underwater forms and dive attractions. Image Credit: flickr.

Thank you, Dr. Allen & Ms. Groom, for a great semester!

Field Trip Post: Number Three

To see a live view of the weather in Roatan, my favorite resort hosts live views of their resort which are updated every 45 seconds and can be viewed here.

Because it is Spring in Roatán, let's simply focus on thunderstorms.

Each thunderstorm has three stages:

Updraft Cumulus Stage

In Photo 1.1, below, you can see the warm air being lifted up vertically, which is resulting in large, vertical cumulus cloud formations.

Photo 1.1 - Warm air updrafts, Image Credit: Flickr

Photo 1.2 - Transition from Updraft Cumulus Stage to Mature stage, Image Credit: Flickr

In Photo 1.2, above, warm air has mixed with surrounding seawater, the warm air has risen vertically, which has created cumulus cloud formations.

Mature Stage

In this stage, warm air has risen above the freezing level and condensed. There are strong downdrafts that are pulled down by precipitation. In Photo 2.1, below, moisture has condensed in the clouds on the left part of the picture, and light rainfall is visibly present (shown by the blue arrows).

Photo 2.1 - Light Precipitation and Downdrafts, Image Credit: Flickr

Photo 2.2 - Heavy Rainfall and downdrafts, Image Credit: Flickr

In Photo 2.2, above, moisture has condensed, many downdrafts have been brought down by precipitation and this has produced a heavy rainfall.

Dissipating Stage

The resultant rain has cooled the surrounding air, and air then flows out of the storm - which creates high winds.

Photo 3.1 - Strong Winds, Image Credit: Flickr

In Photo 3.1, above, the rain has decreased in intensity, the rainfall has cooled the air surrounding the storm, which has caused strong winds, shown by the trees at the bottom of the photo.

Field Trip Post: Number Two

Roatán is mostly known for its beaches and underwater landscapes, however there are quite a few scientific interests inland that also happen to be picturesque.

Let's look at Weathering:

Physical

The mix of warm Caribbean air during the day, cool temperatures at night and exposure to a high salt content from the splashing waves of the Caribbean sea create a highly potent combination. Essentially: fluctuations in temperature and salt from the water (and subsequent internal crystallization) take advantage of the fractures the rock and weather the rock.

Image Credit: Flikr, adapted for purposes of demonstration

Image Credit: Flikr

Notably: the salt weathering has also caused the petrification of these wooden posts which used to make up a pier.

Image Credit: Flikr

Chemical

Constant hydration/dehydration has reacted with any mineral present and created Spheroidal weathering to this rock. Any production of grus has most likely eroded away due to it's proximity to incoming/receding waves.

Image Credit: Flikr

Let's Look at Soil:

Because the island is a volcanic form, it is relatively all rock beneath the surface. Weathering and breaking down of superficial rock surfaces, decomposition of organic matter on top of the rock and strong leeching of soil on and in rock fractures has created a process of laterization. This has created oxisols (soil) on the surface, which enables plants to grow on top of rocky areas.

Image Credit: Flikr, adapted for purposes of demonstration

Image Credit: Flikr

Sources Consulted:

Ritter, Michael. "Soil Forming Processes." University of Wisconsin-Stevens Point. 1 Oct. 2009. Web. 02 Mar. 2011.

Field Trip Post: Number One

Roatán, (16.34°N 86.33° W) lays across the Cayman Trench at the northwestern intersection between the Caribbean and North American Plates.

Image Credit: Purdue University

The easiest way to describe Roatán's formation is to say that through a process of transforming plate interaction and a parallel process of divergence between the North American Plate and Caribbean plate, magma was allowed to escape from below the earth's crust. The transform process allowed the sub-aquatic magma to cool (through an exothermic process) and form the resultant igneous rock - which eventually ended up forming the Bonacca Ridge, which resides underneath the Bay Islands, and more importantly: Roatán.

Because magma was moving from an area of high pressure to low pressure, magma moved through dikes to reach the ocean floor, and the basalt lava flows allowed centuries of compiling igneous rock to eventually form the ridge islands.

It would not be completely absurd to assume that a process of extension faulting allowed some of the material of the ridge to move in certain ways that effect its height (which would account for the fact that pats of the island are at a higher elevation than others).

Areas where the plates were convergently moving created areas of anticline folds.

Interesting Look at the trough surrounding Roatán and the Bonacca Ridge, Courtesy: Stanley Submarines

Sources Consulted:

"Island Geography." Tourism Roatan. Web. 14 Feb. 2011. http://tourismroatan.com/about-roatan/geography

Mann, Paul. Geologic and Tectonic Development of the Carribean Plate Boundary in Northern Central America. Boulder, Colo: Geological Society of America, 2007. Print.
http://books.google.com/books?id=CvmNCC0W97wC&pg=PA52&lpg=PA52&dq=bonacca+ridge+formation+site&source=bl&ots=jyciKoT7y-&sig=bXI8l-tB3FU2SjqQ9dCAzgFLuv8&hl=en&ei=rf9aTaSmB4r6sAPz_9COCg&sa=X&oi=book_result&ct=result&resnum=1&sqi=2&ved=0CBMQ6AEwAA#v=onepage&q&f=false

Rogers, Robert. "Chapter Two Figures." Geology at CSU Stanislaus.
Web. 14 Feb. 2011. http://geology.csustan.edu/rrogers/Rogers2003/chpt2_figs.htm

Geography 1202 Introduction

Welcome, I'm Christian van de Werken. I'm a junior studying Business Administration with a specialization in Finance Management at the University of Colorado.

For my physical geography 'field trip' assignment, I have selected the island of Roatán - the largest of the four Bay Islands off the coast of Honduras. I chose this location because I've visited it on past vacations, dove many parts around the island, found the environment to be incredibly beautiful and plan to return to Roatán over the summer of 2011 to get my Dive Master certification (with a fresh supplementary scientific understanding of the locale).

Roatán is incredibly beautiful from land,

remarkably tranquil from the air

and has a powerfully dazzling ambience underneath the ocean surface.

Over the duration of this project, I will adhere to the grading criteria by providing geographical information, but will do so with photos and experience from my previous visits used to substantiate my arguments.

Throughout the course of this semester, I hope to gain knowledge that will not only educate me about the Honduran island, but also about the natural environment that surrounds me. I look forward to a successful Spring 2011 semester in Dr. Casey D. Allen's Physical Geography 1202 class!

*All images are owned by me and have been posted from my personal archive*