228 



I. II. III. 



Si0 2 ... 58-300 ... 52-600 ... 51-100 



A1 2 3 ... 20-990 ... 17-315 ... 22-051 



Fe 2 3 ... 1-660 ... 1-722 ... 1-210 



FeO ... 6-343 ... 12-043 ... 5.885 



CaO ... 8-512 ... 7-728 ... 11-424 



MgO ... 3-964 ... 3-252 ... 2-346 



Na 2 ... 2-456 ... 2-622 ... 2.216 



K 2 6 ... -926 ... 1.486 ... 1-022 



P 2 ... -102 ... -153 ... 179 



C0 2 .. -320 ... -140 ... 1-820 



Loss 1-120 1.160 -710 



99-693 100-221 99-963 0) 



I. Micro -porphyritic lava forming bed 12 in WARD'S section. 

 II. Compact lava forming bed 13. 

 III. Porphyritic lava forming bed 15. 



Many of the valleys which drain the northern side of the hilly district 

 running from Skiddaw to Carrock Fell contain boulders of porphyritic 

 rocks resembling to some extent the labradorite-pyroxene-porphyrite of 

 Eycott Hill. The rocks are in general lighter in colour than those of 

 Eycott Hill. A specimen from Roughten Gill contains small patches, about 

 equal in size to some of the porphyritic felspars, but without their charac- 

 teristic form, consisting of aggregates of zoisite, calcite and chlorite. The 

 zoisite occurs in long colourless prisms with a well marked cleavage parallel 

 to the prisms and cross jointing at irregular intervals. It is colourless and 

 possesses moderately strong refractive power. The prisms give straight 

 extinction and polarize in the weak bluish tints of the first order. 



An interesting question arises as to the connection between the plutonic 

 rocks of Carrock Fell and the volcanic rocks of Eycott Hill and the 

 northern part of the Skiddaw region. Mr. WARD regarded the former as 

 the metamorphosed representatives of the latter. May they not rather in 

 part represent the same magma cooled under plutonic conditions ? Some 

 of the quartz-gabbros or augite-diorites certainly resemble the Eycott Hill 

 lavas in composition. 



West of England. The basic igneous rocks of the West of England 

 belonging to the group now under consideration the so-called green- 

 stones are of exceptional interest on account of the extent to which 

 they have been metamorphosed by the post-carboniferous earth-move- 

 ments, and by the intrusion of large masses of granite. Devon and 

 Cornwall, together with Brittany constitute a part of an old chain of 

 highlands which formed a marked feature in the physical geography of 

 northern Europe during Mesozoic times. The Devono-Carboniferous and 

 pre-Devonian rocks of which this chain was composed are concealed at 

 intervals by Mesozoic and Tertiary strata, but wherever they come to the 

 surface, as is the case in the Ardennes, the Eifel, Westphalia, Nassau, 



(1) These analyses are given in Mr. WARD'S paper as adding up to 100 in each case. 



