Welcome to Xiaoliuqiu — An Island of Geological Wonder (FOSSILS)
In this Earth Cache, you will learn about limestone — a unique kind of rock that is made up of lots and lots of fossils, in particular coral, sponges and mollusks. And you won't just be observing lots and lots of limestone rock here at Secret Beach — no; you will instead be observing a plethora of those sponge and mollusk fossils that are right here in front of your eyes and learn why there are so many fossils here at this location. Upon learning all there is to know about the Earth Science behind fossiliferous limestone or limestone containing fossils, 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 Fossil 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 Limestone Exactly and Why Does Xiaoliuqiu Contain so Many Fossils?
Xiaoliuqiu is a coral island — the only one in Taiwan! This means that its entire land here is made up of a kind of rock that used to be under the ocean. And through the powers of Mother Nature, that rock slowly emerged itself above land and created what we know as Xiaoliuqiu today.
So how exactly did this limestone form in the first place? Well, ocean-dwelling creatures such as coral, sponges and mollusks here used calcium carbonate — a special kind of chemical found in seawater. These sea creatures use this chemical to create their shells and bones. As these organisms died, their shells and bones were broken down by waves and settled on the ocean floor here at Secret Beach where they were compacted over millions of years. The sediments and the pressure of the ocean water caused the remains of the animals to be "hidden" or "cemented" within this compacted material, thus creating the limestone or rather fossiliferous limestone all around Secret Beach.
So, if these creatures of old are "hidden" within the limestone rock themselves, how is it possible to see them? I mean, they are "hidden" right? So that means we'll have to break open the rock to see them? Well, yes and no. You could break open the rocks but that would be very bad and very unacceptable — one, we Geocachers practice a Leave No Trace policy, and two, we want the fossils of old to remain in their current state for as long as possible to keep the environment looking pristine and help the current creatures have homes to stay in. So, how can we see these "hidden" fossils? Easy. Mother Nature has already helped us! Yep, She worked her "magic" and helped expose these fossils within the rocks. How? Through chemical weathering. You see, limestone is susceptible to being dissolved when it comes into contact with rain, especially when that rain combines itself with carbon dioxide and creates acid rain, thus wearing away the rock and exposing the fossils within. And that's not the only way Mother Nature has helped with showing us these hidden fossils. Biological weathering has also been responsible too. Other organisms use the rocks for shelter or other means so will use their "magic" to dissolve the rock itself, thus exposing the fossils. And there's even one more way these fossils have come out from hiding — and that is through attrition, which is when the ocean waves carry small pebbles or sand and these things act as "sandpaper" against the rock, smoothing them out or breaking them apart, thus exposing the fossils. And there you have it! Fossils Exposed! Granted this process does not happen overnight and has taken millions and millions of years to do but it is quite interesting if you ask me to be able to see the results of millions and millions of years of chemical weathering, biological weathering, and attrition.
So What Kinds of Fossils Can Be Found along Secret Beach?
As Xiaoliuqiu is an island so it is thriving with marine life, especially coral, sponges, and mollusks, and these fossil remains are everywhere! But not just the fossilized shells of these creatures can be found. There are also cast fossils of other creatures too! These are the imprints of past creatures upon the rock themselves. Also, you can observe trace fossils and true forms along the limestone of Secret Beach. Trace fossils are evidence of the animal's "behavior" and not their actual selves, meaning you can observe teeth marks or a burrow or sorts indicating something about the past life of that creature. And true form is a remnant of the actual creature itself like its shell or other body parts, which you will see plenty of here at Secret Beach. Below you can see what the fossils of sponges and mollusks look like:
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Logging Requirements
Xiaoliuqiu is indeed an island of so much geological wonder and here at the Posted Coordinates, you will be brought to a special place — Secret Beach — where lots and lots of fossils remain.
Please Note: Come to this area during low tide only in order to view the fossils. Also, make sure to "explore" the area a bit and don't limit yourself to just the "small" area of the Posted Coordinates only.
In order to log a Found It! for this Earth Cache, please go to the Posted Coordinates (and beyond a little) to complete the following tasks:
1. Based on what you have learned about the two main kinds of animal fossils here — sponges and mollusks
- How "complete" are the fossils? (How much of them can you see?)
- Approximately how big are the fossils (length / width)?
- Where exactly on the rocks are the fossils located?
- What kind of fossil would you say there were — cast, trace, or true form?
- Do the fossils look like they are going to "fall out" very soon or will they "stay" a long time?
What do all these things above tell you about the overall weathering and erosion of this area? How did you come to your conclusions?
2. Based on what you have learned about the three kinds of fossils — cast fossils, trace fossils, and true form fossils — which kind of fossil were you able to observe more of? Why do you think this is so? Also, what do these remnants tell you geologically about the life and/or behavior of these animals? How did you come to your conclusions?
3. Send me a photo (or photos) via the Geocaching Messenging Center showing one example of each of the three kinds of fossils you observed here and identify which creature you feel they most represent.
4. Based on what you have learned about fossils and their connection to chemical weathering, biological weathering, and attrition, what is the future of these fossils? What natural ways can you observe here that could continue to preserve and protect them?
5. Optional — Post a photo of yourself or a "Geocaching" item identifying yourself here at "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 hunting for Fossils at Secret Beach.