1866.} JUKES OLD RED SANDSTONE AND DEVONIAN. 349 



beds were perpendicular, the cleavage certainly dipped north-north- 

 west at ed"". 



Higher up the valley of the Barle, the rocks and the scenery were 

 precisely those of many valleys about Glengariff and Killarney. In 

 the lane going up from Ashwick Bridge (a mere foot-bridge called 

 "a clammer" over the Barle) to Dulverton common and there- 

 abouts, there were many small exposures of rock, of which the fol- 

 lowing notes occur in my note-book : — " purple sandy slate with 

 grit-bands, strike east-north-east, perpendicular, genuine Old Eed 

 Sandstone of Ireland." " Cleaved red sandstone, or sandy slate, pre- 

 cisely like Old Red Sandstone of Ireland, dip south-south-east at 40°." 



Pig. 10 will give a general idea of the facts to be observed near 

 Dulverton. 



3. Dulverton to Bunster. — Having thus satisfied myself that the Old 

 Red Sandstone below, and the Carboniferous Slate above, were con- 

 tinued thus far to the east without any material change in their 

 characters from those that they possess in the Barnstaple country, I 

 proceeded to explore the country to the north, and took the road to 

 Dunster. I was disappointed in the sections on the sides of the Exe, 

 north of Chilly Bridge. There are only occasional small road- cuttings, 

 showing pale greenish-grey soapy slate, in which I was unable to 

 determine the bedding with anything like certainty. 



These rocks are evidently the " Green * Chlorite Schist with quartz 

 veins" of Sedgwick and Murchison, appearing to dip under the 

 " schists and thick sandstones, red and variegated," which are as 

 obviously the rocks which I have just spoken of as Old Red Sand- 

 stone. The two kinds of rock were nowhere exposed in any close 

 proximity to each other. 



Respecting some cuttings a little S. of Exton, I find in my note- 

 book a remark to the effect that '^ it is not easy to distinguish these 

 from some parts of the Carboniferous Slate ; " though when I wrote 

 that, I was under the thorough conviction that I was deep in the Old 

 Red Sandstone, or in some still lower formation. The cleavage here- 

 abouts dipped to the south at 40°, and the beds at first sight seemed to 

 coincide with it ; though patient hammering disclosed in some places 

 what appeared to be the lamination of deposit dipping northwards. 

 At Eyeson Hill, between Exton and Wheddon's Cross, an iron-mine 

 was opened on a green hill-side, from which a considerable quantity 

 of haematite had been extracted. Reaching Wheddon's Cross, which 

 stands on the crest of the watershed between the basin of the Exe 

 and that of the Dunster brooks (and appeared by my aneroid 

 barometer to be about 830 feet above the sea), I went to examine 

 some old lime-quarries there. In these there were beds of grey 

 slate, becoming in some places very calcareous, and also inclosing 



* The green colour in sandstones and slates was formerly attributed to the 

 presence of chlorite, without hesitation. It is probably quite as often due to the 

 presence of the silicate of protoxide of iron. With respect to these slates I 

 believe that the green colour only appears on the weathered surfaces, and that 

 when quarried they yield dark-grey or black slates. In each case they have often 

 a peculiar lustrous surface and soapy feel. 



