68" Proceedings of Philosophical Societies. [JAwi* 



Sieiss to that which lies below it, and in crossing the rid^e to 

 ochmore, the quartz is again found on one of the inferior 

 sammits. 



In Ben Ay, Ben KHbrigg, andotherpartsof Sutherland, there 

 appears a gradual transition between the two rocks ; the gneiss 

 first assuming the aspect of micaceous schist, which then 

 passes into a micaceous and highly schistose quartz rock, and 

 ultimately into pure quartz. 



In many parts of the coast of Sutherland, quartz rock is 

 found alternating with red sandstone, both in single beds and in 

 mountain masses. The same appearance^ are observable in 

 several parts of Ross-shire. The quartz rock of which the 

 entrance of the eastern side of Loch Eribol is composed, and 

 which is remarkable for the magnitude and number of the caves 

 which it forms, contain pyrites in considerable quantity ; and in 

 consequence of the decomposition of the substance, is frequently 

 stained of a reddish brown colour so as to resemble granite. In. 

 this neighbourhood the quartz rock presents examples of consi- 

 derable curvatures. 



In the district of Mar, Dr. Macculloch has found a perpetual 

 alternation of gneiss and micaceous schist with quartz rock, and 

 the apparent transition between the two is so perfect that with- 

 out a minute examination of the fractured rock, it is impossible 

 to determine which it presents. In the northern parts of Aber- 

 deenshire, this association is less common. 



The last conjunction of quartz rock observed by Dr. Maccul- 

 loch consists of a repeated alternation with micaceous schist, 

 chlorite schist, and hornblende schist. This series extends over 

 a considerable tract of country in a regularly stratified manner, 

 the beds of the different rocks rarely exceeding a few yards, and 

 often being only a few inches in thickness. 



Quartz rock has not been hitherto found to contain any 

 imbedded minerals, except pyrites and garnets. 



Nov, 17. — The " Description of a Visit to the Nilghurries, a 

 Range of Hills in the Coimbatoor District," (East Indies) by- 

 Nathaniel Kindersley, of the Madras Civil Service ; communi- 

 cated by B. Babington, Esq. was read. 



Dec. 1. — A letter from G. Mantell, Esq. accompanying the 

 drawing of a fossil vegetable from the Sussex sandstone, was 

 read. 



This specimen, which is from the beds of sandstone that occur 

 in the Oak-tree Clay of the south-eastern part of Sussex, derives 

 additional interest from the circumstance of its being associated 

 with the remains of the Ichthyosaurus, and of some species of 

 Lacerta. It bears a closer affinity to the EupherbiaB than to any 

 other recent vegetable ; and it strikingly resembles the fossil 

 plants of the gritstone of Derbyshire and other places. 



A paper "On the Valley of the Sutleig River m the Himalaya 

 Mountains," by H. T. Colebrooke, Esq. VPGS. was read. 



