Folly Dolly Falls
A walk to Folly Dolly Falls, Meltham, to look at the rocks and landscapes
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The rocks of the Meltham area are Upper Carboniferous (Marsdenian) in age, so they are about 310 million years old.
These rocks were laid down in deltas on the edge of a shallow sea, with mountains to the north and south. Sands and muds were deposited by rivers in shallow water. Because the continent was close to the equator, the climate was warm and wet so that tropical rain forest flourished. Dead plant material became trapped in stagnant swamps between river channels. Over geological time it was buried by muds and sands as the rivers in the delta changed position and built up more deposits. The water, oxygen and hydrogen were driven out of the plant remains, leaving only the carbon in coal seams, such as the Upper Meltham Coal.
After the sediments were formed close to sea-
These rocks, particularly the mudstones, contain fossils, such as shells and microfossils,
of which the most important are goniatites. However, fossils are not easy to find
here and the site is best left undisturbed. Goniatites are the ancestors of ammonites
and like the present-
Folly Dolly Falls gives an excellent view, in three dimensions, of a fault. The change
of rock type from less resistant shale to the stronger beds of sandstone has been
exploited by the stream to form the waterfall, which cascades across the sandstone
fault plane, down joints and along bedding places. There is some reddening of the
sandstone by iron-
Grid Reference
SE 107 113
Photo 1922 from Kirklees Photo Archives
The position of the fault is marked by a gully which runs across the front of the waterfall. The soft shale was fragmented and shattered, as the sandstone moved violently against it during fault movements, to form soft clay called gouge, which has been weathered more than the resistant sandstone.
There are very few places in West Yorkshire where beds dip at steep angles and they are nearly always associated with fault movements, as in this case. As the shale moved down relative to the sandstone, it was affected by friction with the sandstone and dragged downwards, forming the drag folding shown above.
This site is privately owned so permission should be sought before a visit is made.
