Shifting Sands of Marco Island EarthCache

This EarthCache is only a short walk from Boardwalk #6 parking at Tigertail Park. I recommend doing this cache at sunset because this is the best part of the island to watch the sunset.

Beaches are formed through the interaction of various natural processes such as wave action, currents, tides, and the movement of sediment. Typically, the process starts with erosion of rocks and cliffs by waves and weathering. The eroded sediment, such as sand, gravel, and shells, is then transported by waves and currents, eventually depositing along the shoreline to form beaches. This process is ongoing and constantly shapes and reshapes beaches over time.

Beach erosion refers to the gradual loss of sand and sediment from a beach, resulting in a reduction in beach width and volume. It occurs when the natural processes that replenish beaches with sand, such as sediment transport by waves and currents, are unable to keep up with the rate of sand removal. Beach erosion can lead to the loss of valuable coastal land, damage to infrastructure, and diminished recreational and ecological value of beaches.

There are six main causes of beach erosion:

1. Wave Action: Waves carry energy, and when they crash onto the shore, they can displace sand and other sediments, gradually eroding the beach. This erosion is particularly pronounced during storms when wave energy is higher. The force of the waves can undercut the base of cliffs and dunes, leading to collapse and further erosion.

2. Tidal Changes: Tides play a significant role in beach erosion. High tides bring more water onto the beach, increasing the potential for erosion by amplifying wave action. Additionally, the constant movement of water during tidal cycles can slowly wear away at the shoreline over time.

3. Wind: Wind can contribute to beach erosion by transporting sand inland or out to sea. Strong onshore winds can push sand away from the beach, leading to the formation of sandbars offshore and a reduction in beach width. Conversely, strong offshore winds can remove sand from the beach, exacerbating erosion.

4. Human Activities: Human interventions along coastlines can disrupt natural sediment transport processes and accelerate erosion. For example, the construction of jetties and groins alters wave patterns and can trap sand on one side, leading to erosion downstream. Similarly, seawalls and other hard structures can reflect wave energy back onto the beach, causing increased erosion. Beachfront development often involves clearing vegetation and altering natural drainage patterns, further exacerbating erosion.

5. Climate Change: Climate change is a significant driver of coastal erosion. Rising sea levels can lead to increased coastal flooding and higher storm surges, which accelerate erosion. Changes in weather patterns, such as more frequent and intense storms, can also contribute to erosion by increasing wave energy and rainfall. Additionally, warming ocean temperatures can affect marine ecosystems, altering sediment dynamics and contributing to erosion.

6. Natural Factors: Geological processes, such as tectonic activity and changes in sea level, can influence beach erosion over long timescales. For example, tectonic uplift or subsidence can change the elevation of coastlines, affecting erosion rates. Similarly, fluctuations in sea level due to factors like glaciation cycles can expose or submerge coastal land, altering erosion patterns. Over geological timeframes, these natural factors interact with other erosional processes to shape coastlines.

Beach vegetation serves as a vital natural defense against erosion along coastlines. Its intricate root systems play a pivotal role in stabilizing the sandy substrate by binding it together. This network of roots creates a strong foundation that holds the sand in place, making it less susceptible to erosion caused by wind and water. Additionally, beach vegetation acts as a natural barrier against wind erosion by slowing down the speed of wind near the ground, reducing the force of wind-driven sand movement. Furthermore, the presence of vegetation helps dissipate the energy of incoming waves, diminishing their erosive force and preventing the removal of large amounts of sand from the beach. Some species of beach vegetation, particularly dune grasses, also trap blowing sand, leading to the accumulation of sand around their stems and roots. This process contributes to the formation and stabilization of sand dunes, which serve as natural barriers against erosion and provide additional protection to coastal areas. Overall, beach vegetation plays a crucial role in maintaining the stability and resilience of coastal ecosystems, while also providing valuable protection against erosion and other coastal hazards.
 

To log this EarthCache, please send the answers to the following questions to me through geocaching.com (failure to do so or posting the answers in your log will result in your find being deleted.):

1. Do you see any evidence of beach erosion taking place at GZ? If so, which of the six types is it?

2. Take note of the beach vegetation to the East, do you think that it is preventing beach erosion? If yes, what do you see that makes you think so?

3. Take note of how large the beach is at this particular location in comparison to the south end of the beach. Based off your research what do you think caused so much sediment to wash up here to create such a large beach?

4. (Can be included in your log.) Post a picture of you or your GPS at GZ with the water in the background.