302 PRCF. T. G. BONNEY ON THE [May I9CO, 



quartz, in the Lower Keuper conglomerate at Alderley Edge (1891). 

 In the Keuper, also, I think that we can trace the gradual setting 

 in of ' inland-sea ' conditions. I am content to take Mr. Jukes- 

 Browne's own map of Britain (' Building of the British Isles/ pi. 

 facing p. 198) at this epoch, and ask whether it does not suggest 

 that the inland sea then occupied valleys which once had opened 

 towards the south ? So far as I understand the physical geography 

 of our region in the earlier and greater part of Mesozoic times, 

 everything points to the existence of large land-masses towards the 

 north and west, of which Scandinavia, Scotland, parts of Ireland, 

 probably also Cornwall, Normandy, and Brittany are remnants. 1 



The quiet transition from Keuper to Rhaetic, the disposition of 

 the various sediments throughout the Jurassic period, the march of 

 its fauna from the French to the British area, all point to land, 

 probably continental, on the north and west, bordered or pierced 

 by a sea opening towards the south-east. Reversals of drainage, of 

 course, may occur, but I am not acquainted with any evidence to 

 show that this happened either before or during the Mesozoic era. 

 Did the Bunter rivers run northward, we might indeed exclaim 

 with Tennyson : 



' The hills are shadows, and they flow 

 From form to form, and nothing stands.' 



But in one direction we find the physical and lithological con- 

 ditions very nearly satisfied — namely in Scotland. It is needless 

 to repeat what I have published about the correspondence of the 

 quartzites, the quartz-felspar grits, and the felstones generally in 

 that country and in the Midland Bunter ; I will only add that in 1892 

 I examined the conglomerates in the Lower Old Bed Sandstone in 

 the neighbourhood of Callander, at Rothesay, and at the base of the 

 Carboniferous system near Brodick. In them pebbles of vein-quartz 

 abound, such as we find in the Midlands, and I obtained, though 

 more sporadically, varieties of the quartzites, the quartz-felspar 

 grits (sparingly), and felstones, some of which appeared identical 

 with those in the Bunter. These were mingled with a number of 

 schistose grits in more or less angular fragments, with an occasional 

 piece of schist or of granitoid rock. The latter, especially the 

 schistose grits, which are rather perishable, are generally missing in 

 the south, and the former set of rocks, I think, is rather more 

 rounded there ; but though the proportions are altered, many pebbles 

 are common to the Scottish and the English conglomerates, and the 

 matrix of the one is practically identical with that of the other. 



The tourmaline-rock among the Bunter pebbles, I admit, presents 

 a difficulty, for this mineral is rare in Scotland. It is not, how- 

 ever, unknown. Mr. Teall has shown me specimens from contact- 

 metamorphic rocks at Knocknailing (New Galloway), in sillimanite- 

 gneiss from Kincardineshire, and in pebbles of a quartz-schist which, 



1 I referred to this, and briefly indicated how the occurrence of some rocks 

 identical with those that occur in Scotland might be explained, in Geol. Mag. 

 1895, p. 79. 



