The Pembrokeshire Coast National Park displays a greater variety of geological features and associated landforms than any equivalent area of the same size in the British Isles. The coastal scenery was the prime reason for the National Park's designation.
Pembrokeshire has 50 Geological Conservation Review (GCR) sites, of a total of only c.400 in the whole of Wales. These sites are, at least, of national significance and some are of international importance. T
The cache coordinates are located on St David's Head, a prominent headland in Whitesands Bay.
The primary rock type on St Davids Head is gabbro; an igneous rock (meaning the rock has been formed from prehistoric lava flows) Gabbro is an intrusive and mafic igneous rock. This basically means it is high in magnesium and iron compounds. Mafic igneous formations are created in lava flows which weren't very thick (low viscosity)
The cache coordinates take you to a small cave which is in the side of St David's Head. Access is easy from the Pembrokeshire Coastal Path however care must be taken as there are steep drops and rocky areas nearby. I wouldn't recommend this cache is undertaken in stormy weather.
The gabbro is formed in distinct layers or planes as they are known geologically.
This cave will have been formed through a long process of erosion causing weaknesses in the bedding planes and the inevitable collapse of the gabbro structure.
Further erosion is caused by the process described in the image below.
In order to claim a find on this earthcache please perform the following tasks:
1) Estimate the width of the cave inside at its widest point.
2) Estimate the height of the cave inside at its highest point.
3) Describe the texture of the gabbro inside the cave and outside the cave. Can you think of any reasons for this?
4) Which weathering process do you think the cave has been formed through? Please explain your reasoning.
Please email your answers through my geocaching profile. You don't need to wait for confirmation from me before logging.
Pictures are appreciated but not compulsory.
Thanks to the St David's NT for permission.