Slate, gray, fine-grained, clayey metamorphic rock that cleaves or splits, readily into thin slabs having great tensile strength and durability; some other rocks that occur in thin beds are improperly called slate because they can be used for roofing and similar purposes. True slates do not, as a rule, split along the bedding plane but along planes of cleavage, which may intersect the bedding plane at high angles. Slate was formed under low-grade metamorphic conditions—i.e., under relatively low temperature and pressure. The original material was a fine clay, sometimes with sand or volcanic dust, usually in the form of a sedimentary rock (e.g., a mudstone or shale). The parent rock may be only partially altered so that some of the original mineralogy and sedimentary bedding are preserved; the bedding of the sediment as originally laid down may be indicated by alternating bands, sometimes seen on the cleavage faces. Cleavage is a super-induced structure, the result of pressure acting on the rock at some time when it was deeply buried beneath the Earth's surface. On this account, slates occur chiefly among older rocks, although some occur in regions in which comparatively recent rocks have been folded and compressed as a result of mountain-building movements. The direction of cleavage depends upon the direction of the stresses applied during metamorphsim.
To claim this Earth Cache, please email me the answers to the following questions:
1) How big are the obvious areas of slate within the sandstone cliffs at the posted coordinates?
2) Roughly how high are these cliffs?
3) What direction are the slate cleaveages running? What is the angle of the cleavage?
4) Do you think this slate is fully formed are partially? And why?
5) Post a picture of yourself / group at the posted coordinates with the slate in the background. Feel free to post the pictures in your log, but email me the answers. Enjoy the beach and please be respectful of the area.