Vol. 65.] PETROGRAPHY OF THE NEW PvED SANDSTONE. 243 



The climatic conditions 1 under which the Lower Breccias and 

 Sandstones were deposited have been discussed for these and similar 

 rocks. The idea of the existence of desertic and lateritic conditions - 

 is, it seems, made more tenable when we consider the prevalence 

 of millet-seed sands and the increased proportion of plagioclase- 

 felspars 3 in these deposits. 



The Lower Marls, and the Upper Sandstones and Marls, as regards 

 composition, appear to be the most uniform members of the New 

 Eed Sandstone, a fact explained partly by their lithological character 

 and partly by their mode of deposition. As stated before, they 

 have evidently had a more complex source than the other members 

 of the New Eed, and were deposited chiefly from sediment-bearing 

 currents which had no constant direction for any length of time. 



Again, in the case of the Upper Sandstones and Marls it is most 

 difficult, in view of their transgression northwards and westwards 

 on to older rocks, to say how much of the material of which they 

 are composed is of direct origin from the parent source, and how 

 much has been derived from pre-existing New lied depi sits. 



Such problems will only be possible of solution when the petrology 

 of the older sedimentary rocks has received adequate attention. 



In conclusion, I wish to express my indebtedness to Prof. Sollas 

 for much assistance and encouragement during the early stages of 

 this w ork ; to Mr. Ealph Morgan and Mr. Kobert Hancock, of 

 Exeter, as also to Mr. W. G. Churchward, F.G.S., of Teignmouth, 

 for their kindness in collecting for me many samples of the New 

 Eed rocks ; and to Mr. Ussher, F.G.S., for allowing me to work on 

 material collected by him in Somerset. 



EXPLANATION OF PLATE XII. 



Fig. 1 a. Anataso : group of crystals in parallel growth, tabular parallel to the 

 base {00l}, from the Pebble-Bed of Newton Poppleforcl (Devon). 

 X about 115. (See pp. 231-32.) 

 1 b. Anatase, with low pyramids of such form as {hh l}, from the Lower 

 Breccias of the Ness, Teignmouth (Devon). X about 100. (See 

 p. 232.) 



1 c. Anatase similar to fig. 1 a, from the Lower Sandstones of Honiton 



Clyst (Devon). X about 200. (See pp. 231-32.) 



2 a. Brookite, pale-yellow crystal from the Lower Breccias of the Ness, 



Teignmouth (Devon). X about 250. (See p. 238.) 

 2 b. Brookite, an almost colourless, somewhat rounded crystal, from the 



Lower Marls of Raddon Quarry, near Thoverton (Devon). X about 



250. (See p. 238.) 

 2 c. Brookite, an almost colourless crystal, from the Lower Sandstones of 



Monkerton, near Pinhoe (Devon). X about 1000. (See p. 238.) 



1 J. G. Goodchild, Trans. Geol. Soc. Edin. vol. vii (1893-99) p. 203 ; and 

 J. A. Phillips, Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 110. 



2 J. J. H. Teall, Proc. Geol. Assoc, vol. xvi (1899) p. 148. 



3 W. Mackie, Trans. Geol. Soc. Edin. vol. vii (1893-99) p. 443 ; see also 

 T. G. Bonney, Proc. Liyerp. Geol. Soc. vol. ix, pt. ii (1902) p. 220. 



