The posted coordinates are across the street from the rock formation that is the subject of this EarthCache. Please don't cross the street. It’s safer, and you don’t need to touch the rock to answer the questions.
The rock formation you see before you is typical of the Bermuda landscape—you will see it all over the islands. You are looking at what was part of a series of sand dunes that helped bury Bermuda’s volcanic past.
The islands of Bermuda are the remnants of volcanoes that arose 110 million years ago. After they cooled, coral reefs formed in the shallow, tropical waters. The remains of the coral and the skeletons of creatures that fed off the reefs fell to the sea floor, creating limestone rock as time passed. During the Great Ice Age, the sea level fell, exposing the sea beds. Winds helped erode the limestone, blowing the bits and pieces across the beaches and piling them up into sand dunes. Plants grew and spread, stabilizing them, and acidic rains fell, both cementing the dunes into rock and leaving behind tiny holes that made the rock roughly-textured and porous.
Although limestone is a sedimentary rock, you don’t usually see a clear stratification pattern like you do with other sedimentary rock types composed of a mix eroding minerals and igneous rocks on the surface. Limestone is usually composed of microscopic organic remains and deposited underwater in seas and oceans. The limestone here is different because waves and winds eroded the original limestone sea beds and deposited sand-sized particles in visible layers that built up into dunes over time.
To claim this EarthCache as a find, please send me the answers by email or the message system within 5 days of your log. If you fail to send the answers to the geology questions, I will have to delete your log as per EarthCache rules.
1. Winds create sand dunes by blowing particles uphill once they start to pile up in a sheltered spot. What direction did the wind blow to deposit the rocks you see before you?
2. What is the angle of the rock layers at Ground Zero?
3. In your own words—why do you see rough, visible layers here instead of the usual smooth look of the limestone used in most building materials?
4. This is totally optional--post a picture of yourself with the town of St. George's in the background. Please don't post any spoiler pics of the rock wall. Thanks!
Sources:
Thanks to my Uncle George, professional geologist, for picking the spot and helping me come up with the lesson!
https://static1.squarespace.com/static/501134e9c4aa430673203999/t/5775252215d5db613ab615fe/1467295011250/The+Geology+of+Bermuda_RChandler.pdf
https://sciencing.com/difference-between-sandstone-limestone-6060787.html