Maracas Beach - Earthcache EarthCache
Maracas Beach - Earthcache
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Welcome to Maracas Beach. We hope you enjoy your visit and our Earthcache.
Completing this Earthcache: We placed the questions at the top of the Cache page so you will be sure to have them on your GPS. To get credit for completing this Earthcache, please submit to us through our Profile an EMail with your answers to the following questions (you do not have to enter the water to be able to answer the questions).
1. Estimate how high the highest waves are in feet (or metres). Are the waves breaking far from shore, or close to shore?
2. Do you think these are constructive waves, or destructive waves?
3. Are the waves coming in at an angle to the shore today?
4. In a bay, what process causes waves to come straight at you when you are standing on shore?
5. Based on your observations of the waves today, the shape of the beach looking from east to west, and the aerial photo provided in the description, do you believe that longshore drift is occurring in this bay?
Photos of your caching party or your gps at GZ, or just a few nice photos of the beach are welcomed, but are optional.
Maracas Beach
The Northern Mountain range, where Maracas Beach is located on the north coast, is made of low-grade metamorphic rock which is resistant to wear and generally creates rocky coastlines with a mixture of headlands, bays, and beaches (see the aerial photo of Maracas Bay). The north coast of Trinidad is constantly being affected by the action of the ocean's waves which are generated by the prevailing northeast winds. Parts of the coast are eroded or worn away by these waves creating bays. The small bits of rock and sand are transported and deposited into these bays. This is how Maracas Beach was formed.
Bays
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, because the surrounding land blocks some waves and usually reduces the wind strength. Bays are sheltered openings that are found between the headlands that jut out into the sea. If you look North out to sea, you will see the opening to this bay and the headlands on either side of the opening.
Refraction
Waves entering shallow water (like Maracas Bay) slow down while the waves in deeper water continue at their original speed. This results in refraction which is the bending of waves so that wave energy is concentrated at the mouth of the bay, but spread out inside the bays as they lose their energy (see the above diagram). This is why it always looks like the waves are coming straight at you when you’re standing on the beach looking at the ocean. However, waves tend to wash up and down the beach in a slight zigzag fashion, which moves sand along the beach.
Constructive waves build beaches. Each wave is low or breaks far from shore with a lot of foam present (loss of energy). As the wave breaks it carries sand materials up the beach in its tumbling swash. The material will then be deposited as the backwash soaks into the sand or slowly drains away.
Destructive waves destroy beaches. The waves are usually very high, very frequent, and break closer to shore. The backwash has less time to soak into the sand. As these waves continue to hit the beach, there is much more moving water to transport the sand materials back out to sea.
Longshore Drift
Longshore drift consists of the movement of sediments (generally sand) along a coast at an angle to the shoreline, which is dependent on prevailing wind direction (northeast here at Maracas), swash and backwash. This process occurs in the littoral zone, which is close to the surf zone or beach. The process is also known as longshore transport or littoral drift. Longshore currents can generate waves that break at an angle to the beach which results in longshore transport (see photo showing zig-zag action).
If you choose to enter the water (not necessary to complete the Earthcache), you may be able to feel a sideways pull of a longshore current.
Thank you for completing this Earthcache.
Portions of the information presented above have been gleaned from a number of sources such as: Wikipedia, the extended igcse geography class, itc.gsw.edu, and Coastalwiki.
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