CHAP. VIII.] TBIASSIC PERIOD. 119 



The same is the case with the pebble beds in Lancashire ; 

 near Liverpool they consist of reddish brown pebbly sand- 

 stones, and are more than 600 feet thick, but the pebbles 

 are small and scattered, and the group is said to die out 

 between Ormskirk and Preston. In Ireland (Antrim) 

 certain red and yellow sandstones are referred to the 

 Bunter division, but no beds of this age have been recog- 

 nized in Scotland. 



Observations on the lithological characters of these sand- 

 stones and pebble beds have disclosed several important 

 facts. Certain beds of friable sandstone have been de- 

 scribed by Dr. Sorby and Mr. J. A. Phillips, under the 

 name of " Millet-seed beds," the grains of quartz and 

 felspar of which they consist being so completely worn 

 and rounded that the disintegrated sand flows through the 

 fingers as easily as seed or shot. Such sandstones are fre- 

 quent in the Lower Bunter, and occur also in the upper 

 division. Ordinary sandstones consist of more or less 

 angular grains (see p. 4), and Mr. Phillips, after having 

 examined a number of modern sands, states that " none of 

 them, excepting such as had long been subjected to the 

 wearing effects of wind action, were found to resemble 

 those of the Millet-seed sandstones in having all their 

 grains reduced to a pebble-like form. Among these the 

 grains of blown desert-sands most completely resemble 

 those of millet-seed sandstones." ] From these facts we 

 may infer that such sandstones are of seolian formation, 

 and that during the epoch of the Bunter Beds large desert 

 tracts, with their usual accompaniment of blowing sands, 

 existed in the British region. 



The pebble beds have been studied by Professor Bonney 



and Mr. W. J. Harrison. The majority of the pebbles 



consist of vein-quartz or quartzite, and Professor Bonney 



finds that the quartzites differ from any English rock that 



1 " Quart. Journ. Geol. Soc.," vol. xxxvii. p. 27. 



