1) A frequent term in the south Pennines where it referred to a steep-sided ravine and gave rise to numerous place-names.
It can be compared with ‘gill’ which was characteristic of the northen Pennines. Otherwise, references to its use in everyday vocabulary are scarce: 1719 Thomas Robucke ... found a sadle, bridle, etc. all tyed together in a clough on the side of the moor, Lindley. The final ‘gh’ was not always pronounced. In the Huddersfield area Close Gate in Marsden was earlier Cloughs Gate, and Close Hill in Newsome was Cloughs Hill.
2) A spelling of ‘clow’ which developed in those areas where ‘clough’ had the same pronunciation.
1560 the wheylle clogh, Marsden Mill
1754 the sluices and cloughs of the mill, Beeston.