654 BEPOBT — 1888. 



from diorite. The chemical change was greatest where the shearing reached its 

 maximum. In an intermediate stage the rock was a sort of grit, consisting of 

 parallel seams of felspar fragments immersed in chlorite. Much lime was liberated 

 as carbonate. The percentage of silica rose during the process of schist-making 

 from forty-seven to sixty-five. 



In Anglesey additional evidence for the conversion of felsite to mica-schist had 

 been procured. At Forth Nobla a felsitic rock passed into halleflinta, which, by 

 shearing, graduated into schists. The granite of Llanfaelog was intrusive in these 

 and other adjacent rocks. The author's time-succession in the older schists of 

 Ano-lesey could not, of course, be regarded as more than a mineral succession in the 

 lio-ht of the new views of metamorphism. The case was different with the Newer 

 Archfean (? Pebidian) series, in which there was a passage between the hypometa- 

 morphic slates and true crystalline schists, the foliation of the latter coinciding 

 with the bedding, which was clearly indicated by bands of grit. 



6. Slcetch of the Geologt/ of the Crystalline Axis of the Malvern Hills. 

 By Charles Callaway, D.Sc, 3LA., F.G.S. 



This ridge was composed of rocks which had originally been eruptive, but in 

 places they had undergone such important structural and chemical changes that 

 they might fairly be called ' metamorphic' The original rocks were diorite 

 (several varieties)", epidiorite, a binary granite, and felsite The principal rocks of 

 secondary origin were muscovite gneiss, biotite gneiss, hornblende gneiss, and mica 

 schists, some of these schists being simple (formed from one kind of rock), while 

 others were injection schists (formed out of veined masses). 



In the North Hill massive diorites predominated, but a gneissic structure was 

 frequently produced by pressure. The mass, which culminated in the AVorcester- 

 shire Beacon, consisted of diorites with intrusive gi-anite. The granite veins in diorite, 

 accompanied by shearing, gave rise to various gneisses. At the Wv'ch there was a 

 chlorite gneiss, which was a sheared granite, into which chlorite from decomposed 

 diorite had infiltrated. Between here and the "Wind's Point the rock was mainly 

 diorite with granite veins, occasionally compressed and sheared. The Herefordshire 

 Beacon was of similar composition, but its eastern spurs consisted of felspathic 

 rocks, some of which, according to Mi-. Eutley, were perlitic felsites. These rocks 

 were probably of Uriconian (Newer Archfean) age, and might perhaps be cor- 

 related with the Pebidian of Dr. Hicks. 



Granite in masses formed the northern end of Swinyard's Hill ; near the 

 southern end it was sheared into mica gneiss, and at the southern extremity, in 

 association with diorite, it formed injection .schist. Midsummer Hill was mostly 

 diorite. Ragged Stone Hill Avas a complex mixture of diorite, granite, felsite, and 

 epidiorite. At the south-eastern spur felsite was sheared into mica schist, while 

 the south-western spur mainly consisted of a mica schist, which could be traced 

 into a diorite. This schist was overlain unconformably by the Hollybush Sandstone 

 (Cambrian). The bulk of the Malvern crystalline rocks were Older Archaean. The 

 Malvern axis was thus seen to furnish many interesting facts bearing on the origin 

 of the crystalline schists. 



7. Archean Characters of the HocJcs of the Nucleal Ranges of the Antilles. 



By Dr. Persifor Frazer. 



During a visit this year to the south-eastern part of the island of Cuba, the 

 speaker had made some examinations of the rocks which form the nucleus of the 

 spurs of the Sierra Maestra, and there is strong reason to believe of the axial range 

 of the entire island and of Jamaica, Santo Domingo, Puerto Rico, and the Wind- 

 ward Islands as well. From the field observations there made, and an examination 

 of the specimens under the microscope, it seems highly probable that these rocks, 

 instead of being igneous extrusions of the Tertiary period and later, are in reality 

 of much earlier date, and may not be entirely volcanic. 



