SD9163 : Janet's Foss
taken 6 years ago, near to Malham, North Yorkshire, England
Janet's Foss is a small waterfall in the vicinity of Malham. It carries Gordale Beck over a limestone outcrop topped by tufa into a deep pool below. The pool was traditionally used for sheep dipping.
The name Janet (sometimes Jennet) is thought to be a folk tale reference to a fairy queen who inhabited a cave at the rear of the fall. Foss is a Nordic word for waterfall, still used in Scandinavia, and is presented in a number of cases in England as 'force'
The Craven Cracoean Reef Belt (CCRB) is an area of geology from Settle to Burnsall in North Yorkshire related to a Lower Carboniferous (Visean - Brigantian) apron reef situated on the southern limit of the Askrigg Block. A series of rounded hills mark the location of flank and mound carbonate deposits that separate 'shallow' shelf deposits north of the Mid Craven fault from 'deeper' deposits of the Craven Basin to the south.
With the development of a barrier like apron reef along the hanging wall of the Mid-Craven Fault; the ramp deposits of the Kinsley Formation (thickly bedded muddy carbonates affected by tides and storms SD6975 : Carboniferous Coral) gave way to back-reef deposits (thinly bedded pure carbonates) of the Cove and Gordale Formations.
The mounds themselves are mostly massive limestone with some areas containing crinoidal deposits, sponges, corals, brachiopods and stromatolites. The earliest reefal structures are small mudmounds, as movement along the Craven Faults progressed the mounds grew into the larger structures visible today. Swinden Quarry is a great example of a core and flank reef that has been dissected by quarrying.
Also worth seeing is the exposure at Loup Scar SE0361 : Loup Scar (5). Flank limestones has been channelised, infilled and rotated by fault movement. This shows the dynamic active environment that these rocks were deposited. See 'Mississippian reef development in the Cracoe Limestone Formation of the southern Askrigg Block, North Yorkshire, UK' by Waters et al., 2017 for more details.