Undulated green slate
Undulated green slate is a metamorphic stone of sedimentary origin containing many minerals such as quartz, feldspars, mica together with the chlorite that gives it its green colour. It forms as a result of pressure and a relatively low temperature. The fossils that can sometimes be found in slate may be visible if the slate is not undulated. But folding of the ground caused by tectonic movements undulated the slate and partially recrystallised the minerals present when it was formed.