592 PBOCEEDINGS OF THE GEOLOaiCAL SOCIETY. 



Lower or Linton slates to the north of the fault, to the extent of 

 some 15,000 feet, would be the repeated equivalents of those beds 

 to the south of this sandstone range, or the Baggy, Marwood, Croyde, 

 and Pilton beds — the Upper Devonian of most authors, the Carbo- 

 niferous Slate of Professor Jukes. Much care was taken in ex- 

 amining this fault, which is with difficulty traceable on the east in 

 the slates, and along the marshy ground at Langley, and which ap- 

 pears to extend from Chapel Leigh to Langley Marsh, a distance of 

 four miles east and west, Lrom Hawkham through the Oak- 

 hampton-House Quarries, Whitfield, &c., we are unmistakeably in 

 the grey fissile slates of Mortehoe and Morte Bay, which here dip 

 south from 65° to 70°, with cleavage coincident, but in some places 

 nearly vertical; the same system of quartz veins that occurs at 

 Lee, Mortehoe, and Woolacombe occurs here — a circumstance, con- 

 nected with other features, tending to clearly identify their position 

 below the range of the Upper Old Eed Sandstone before mentioned. 

 The New Red sandstone and conglomerate of the lower members 

 (Permian ?) abut against the fault, and conceal the continued strike 

 of the Pickwell and Haddon-Down sandstones between Wivelis- 

 combe and Kingston to the Quantock Hills on the east. At Langley 

 Marsh, marshy ground only determines its position. West of that 

 point all evidence is lost ; it may be assumed, but cannot be proved. 

 It may, however, be owing to the difficulty we have in tracing a 

 fault through highly fissile and nearly vertical slates, without hard 

 or interstratified masses to guide us ; but there is no apparent break 

 or unconformity between the slates of Clatworthy, Tuck Mill, and 

 "Huish Champflower. 



With the overlying gritty, hard, red, micaceous sandstones of 

 Main and Heydon Downs the passage and sections are complete, 

 and may be examined in the brook from Tuck Mill to Washbattle 

 Mills, and along the road above the mill, where the rocks gra- 

 dually change colour from pale-grey to red, becoming marly and 

 fissile gritty slates, and finally passing into the coarse sandstones of 

 Main and Heydon Down. The brook passes over highly inclined 

 slates, with cleavage 80° south, and the junction is clearly shown at 

 the mill-bridge and in the road above it, and also in the gorge lead- 

 ing to Chalich. 



The quarries at Higher and Lower Hhaddon, north of Main 

 Down, situated in the lowest part of the Main Down beds, are 

 opened in micaceous, mottled, marly, red and grey earthy sandstone, 

 thick- and thin-bedded, dipping south from 45° to 60° ; these 

 conditions continue under the north flanks of Main, Heydon, and 

 Haddon downs ; and the sandstone graduates into the slates below 

 through a gradual change of character, as at Woolacombe and 

 Morte Bay. 



At Withycombe, Wiveliscombe, and Main Down we have the 

 same undulations and small anticlinals in the sandstone as seen east 

 of Dulverton and the river Barle ; but it regains its south dip south 

 of Wiveliscombe, and this prevails all along the southern side or 

 flanks. 



