Welcome to Xiaoliuqiu — An Island of Geological Wonder! (BAYS )
In this earth cache, you will learn about coastal erosion — in particular, an "anomaly" known as "differential erosion" and how this force of Mother Nature created an interesting landform right smack in the middle of a long stretch of road here. And that landform is a bay! And the area where this bay is located is known locally as Secret Beach. So upon learning all there is to know about bays and the forces of "differential erosion" that sculpted "The Secret Beach", you will be ready to put on your Earth Science Caps and get geological on location here at Xiaoliuqiu Island. And after you answer the task questions and complete all your Coastal Erosion Studies and Observations (which can all be found at the bottom of this page), you can log a “Found It!” for this Earth Cache. I hope you enjoy! Are you ready? Let's begin . . .
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What is exactly a Bay and how does a Bay Form?
First, what "strange" thing do you notice about the coast as you stand at Waypoint 1? I mean, as you're standing at that location look to the left and follow the coast with your eyes to the Posted Coordinates and then continue following the coast to the right. Isn't it so cool how the rocky coast seems to be a "perfectly" straight line from left to right but once you get to the Posted Coordinates it just "magically" curves inward to form a "private" swimming pool? What you see is a bay — a place along the coast where a section curves inward to form a circle or a near-circle shape, and this "strange" thing you see here is exactly that! So while standing at Waypoint 1 and overlooking this area, you aren't just looking at a picturesque paradise. No, you're looking at "differential erosion" — which is basically erosion or the tearing away of rock or other materials at different rates. Here at Secret Beach, different rocks gave different resistance to the waves crashing into them. In other words, the "strong" or hard rocks didn't allow the forces of hydraulic action or the crashing of waves into the rocks to "break" them whereas the other, "weaker" or softer rocks couldn't "fight" off hydraulic action and therefore "broke" away and thus formed a bay. Below is a diagram outlining this phenomenon.
And a more in-depth analysis of this phenomenon can be seen here:
So, here at "Secret Beach" instead of seeing sandstone or clay, you will see coral limestone as Xiaoliuqiu is the only island in Taiwan that is a coral island. However, coral limestone is known for its durability or "strongness" so therefore won't erode. Even though coral limestone is considered to be "strong", it does absorb water easily and since it is a carbonate rock, it is highly reactive when exposed to acids or even mildly acidic rain water, which is its Achilles' heel and therefore deteriorates.
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Logging Requirements:
Xiaoliuqiu is an island of Geological Wonder with so many unique landforms and hidden geological treasures, with one in particular — The Secret Beach — which is an "anomaly" of a landform where you will observe a bay that "magically" formed right along a "perfectly" straight coastline.
In order to log a Found It! for this Earth Cache, please go to the Posted Coordinates and the one referenced Waypoint to complete the following tasks:
1. First go to Waypoint 1 and find the bay in front of you below the cliff. Based on what you have learned about bays and the charactersitics of coral limestone, which area (left area of right area) appears to be more susceptible to differential erosion? How did you come to your conclusion? (Hint: Observe the waves and their direction/force).
2. Next, go to the Posted Coordinates. Based on your answer to number one, were your observations correct? In other words, as you walk along the coral limestone, what do you notice about the rocks to the right of the bay as opposed to those on the left of the bay? What differences do you notice in these two "neighbors?" Why do you suppose there is such a difference?
3. Based on your knowledge of bays and how they form as well as based on your observations at Waypoint 1 and the Posted Coordinates, why do you suppose that the bay formed at this particular location? In other words, what does the coral limestone of this area tell you about The Secret Beach? How did you come to your conclusions?
4. Based on all your knowledge and observations, how do you think the size/shape of the bay will change over time? How did you come to your conclusion?
5. Optional — Post a photo of yourself or a "Geocaching" item identifying yourself here at "The Secret Beach!"
You may log a Found It! on this cache after you have completed the tasks and emailed me the answers. If there are any issues with your answers, I will contact you. And as a friendly reminder, please do not post any of the answers in your logs. Thank you for visiting this Earth Cache. I hope you enjoy your time here at The Secret Beach.