Welcome to Xiaoliuqiu — An Island of Geological Wonder! (STACKS)
In this Earth Cache, you will learn about coastal erosion — in particular, a unique formation known as stacks, and how Mother Nature helped carve this one-of-a-kind "Vase" located just a few meters from the coast of Xiaoliuqiu Island. Upon learning all there is to know about stacks and the forces that sculpted "The Vase", 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 Exactly is a Stack and how does a Stack From?
Simply put, as the name suggests, a stack is a piece of "tall" or "skinny" rock just literally standing up in the middle of the ocean. Well, not necessarily in the middle of the ocean per se, but standing up a few meters or so from the actual coast. So, how did this stack known as "The Vase" here in Xiaoliu Qiu get here in the first place?
Well, first of all, there used to be a headland here — a piece of land that juts out into the ocean. And over millions and millions of years, that headland was eroded or chipped away at by hydraulic action — the force of the seawater hitting against that headland. This hydraulic action "attacked" areas of rock where there were small cracks, and after many, many, many years of "attacking" these "weak" areas, a cave eventually formed. But of course, the hydraulic action didn't just stop at making a cave — no, it kept on "digging" its way through to the other side to form a big "open hole" right there in the headland. And this "open hole" is known as an arch. But just like the cave, the arch were also "attacked" by powers of Mother Nature so that hydraulic action kept on attacking those "weak" areas of rock around the arch and eventually caused the arch to "lose" its "cap". With no "cap" on the arch we were left with the headland "separated" into two parts — one part was still connected to the mainland while the other part was "lonely" out in the ocean. This "lonely" part is known as a stack and is what you can observe at the Posted Coordinates. But unfortunately, all good things must come to an end and this stack won't stay up forever — hydraulic action will cause it to eventually break and fall, leaving a stump. But don't worry because we still have a very, very, very long time before that happens. Below you can visualize exactly what went on here at the Posted Coordinates:
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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 Vase, which is a stack that looks exactly like a vase! So without further ado, let's get geological here and do ourselves and Earth Cache!
In order to log a Found It! for this Earth Cache, please go to the Posted Coordinates to complete the following tasks:
1. Based on what you have learned about hydraulic action in regards to stack and stump, and based on your observations of "The Vase", would you classify "The Vase" as a "stack" or a "stump"? How did you come to your conclusion?
2. Based on what you learned about headlands and based on your observations here at The Vase, where (how far away and in what direction) is the headland from the vase? What do the locations of the headland and "the vase" tell you about the hydraulic action you observed here? How did you come to your conclusion? (Hint: Observe the ocean currents and where the rocks under the water are in reference to The Vase and "follow" them).
3. *(DURING LOWTIDE:)* While wearing appropriate footwear and attire for the ocean, and of course maintaining the utmost safety:
a. Walk out into the ocean towards The Vase.
b. Walk around The Vase
c. Estimate the circumference of the vase at its "thinnest" point
d. Estimate how much of the vase is underwater during your time of visit
e. At which point and in which direction will The Vase eventually break and collapse?
4. Based on all your observations and what you have learned about headlands, where, if any, could you see remnants of the cave(s) and/or arch(es) that were present before The Vase was formed?
5. Optional — Post a photo of yourself or a "Geocaching" item identifying yourself here at "The Vase"!
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 Vase.