Aysgill Force - A Sandstone Sandwich
Gayle Limestone is seen in the village of the same name where we see a miniature version of Upper Aysgarth. The beck tumbles over steps of this distinctive dark grey limestone - the same bed as seen lower down the dale at the more famous falls. There are many crinoid and brachiopod fossils visible in this rock - and these can be seen easily under the bridge. Note the shale here being undercut in the dark slit just below the wall on the opposite side. Eventually the undercut will be so great that the slab of limestone will snap off causing the waterfall to retreat upstream.
Lovely view of Gayle Beck - with the Gayle Limestone of the Yordedale Series clearly displayed.
We move upstream and leave the Gayle Limestone behind, as we reach a very thick bed of shales, laid down when the sea was very shallow and muddy rivers dominated the deposition. Being so fragile, the shale erodes easily compared to the limestones and sandstones of the series.