140 Jiepotift and Proccedingn — Geologicnl Socicfy of London. 



The sedimentary rocks associated witli the various igneous masses 

 ■comprise the following : — 



LowKii ()li> Red lied marls and saudstouos, with corustonos and conglomeratoa at 

 Sandstonk. tho base. 



/ Diiit/mor/raptits lii/idun Bixls. IMuo-Mack shales, with ono or 

 Ordovician ) moro tliick bauds of j>Tit towards ilio base. 



(Akknig). \ Tityivjiaptiis Beds. IJlaok and butt' shaloswith thin ji^rit bands: 



I tliiok i)!uuls of ashy ^rits and rons^'louieratos towards tho base . 



These rocks are described in detail. They occur in two main 

 anticlines, overlolded, and complicated by thrusts which cut out 

 a great part of the intervening syneline. They are covered 

 unoontbrmably by the lower beds of the Old Ived Sandstone. The 

 igneous rooks occur in three well-detiiiod areas, which belong to the 

 same iietrographical province, near (^oomb, at Capel Bethestla, and at 

 Lanibstone. Both intorbedded and intrusive rocks are represented, 

 and full petrographical descriptions of all types are given in the 

 paper. The latter include diabases, and the large porphyry mass 

 of Lambstone. The extrusive rocks have been determined to 

 occur in the following order: — (1) augite-andesites ; (2) rhyolites; 

 and (3) augite-andesites, with some hornblende-andesite. The 

 extrusive rocks are interbedded with fluxion breccias and with tuffs;, 

 they are associated with the lower members of the TetratjraptHS 

 Beds, and are consequently of Lower Arenig age ; while the intrusive 

 rocks have been injected into the extrusive rocks, and have also 

 affected the Tetnujraptns lieds, but at what date exactly it is 

 impossible to say, exce[)t that it antedates the Old Bed Sandstone. 

 ]\luch of the folding and faulting was accomplished before the 

 Lower Old Bed Sandstone was deposited, but certain faults involve 

 this formation, and make it clear that there was an important later 

 movement. 



2. " The Buttermere and Ennerdale Granophyre." By Robert 

 Heron Kastall, B.A., F.G.S. (Christ's College, Cambridge). 



This paper embodies the results of field-mapping and microscopical 

 study of the large mass of igneous rocks known, collectively, 

 as the Buttermere and Ennerdale Granophyre. From the facts 

 put forward it is concluded that the intrusion is an example of 

 an acid magma, which has crystallized under the peculiar set of 

 conditions that gives rise to a very perfect development of granophyrio 

 structure. These conditions are probably, to a certain extent, 

 intermediate between those of plutonio and true hypabyssal rocks. 

 The masses appear to be of the ' cedar-tree ' laccolite type intrusive 

 about the junction of the Skiddaw Slates and the Borrowdale rocks, 

 but penetrating into the higher rocks. Besides the normal acidic 

 rock, which comprises the bulk of the intrusions, there are some 

 marginal patches of more basic character, showing obvious genetic 

 relationship, and slightly earlier in point of time than the intrusion 

 of the acidic rock. These basic forerunners alVord evidence of 

 dilYerentiation of the magna before intrusion — an example of Professor 

 Brogger's deep magmatic ditfereutiation. Considered as a whole, 

 the ohai'acter of the magma shows closer affinity to the tonalite 



