Dec. 1861.] Geoloyy of the Neilyherries. 239 



to each other, and to the transverse joints. The rock on its wea- 

 thered surfaces is of a white color, and the laminae of Quartz are 

 more distinctly seen. 



4th, 5th, 6th. — Red, white, and green compact granites, con- 

 taining garnets. These rocks are extensively diffused in the neigh- 

 bourhood of Dodabett. 



Compact Felspar enters so largely into the rocks of these Hills, 

 that I am actuated to subjoin a list of those I have met with con- 

 taining it. 



1st. — White Syenite, being nearly all compact Felspar with a 

 few grains of Quartz, and Hornblende, disseminated : the edges 

 of this rock when fractured are sharp and highly translucent — it is 

 occasionally striated with Hornblende. 



2nd. — It passes into red syenite with the same ingredients. An 

 opinion has recently been started, that the Logan Stones common 

 in Britain, are not the works of the Druids, and ancient inhabi- 

 tants ; but the result of decomposition. I have now before me a 

 natural model in red Syenite, of one of those stones, which I found 

 near Snowdon. 



It contributes greatly to sustain the new theory relative to the 

 origin of the Logan Stones. 



The red syenite when decomposing has its surface traversed by 

 cracks intersecting each other. 



3rd. — Brown syenite of the same ingredients and sometimes 

 containing common Felspar. 



4th. — Green syenite, the same ingredients with a highly crys- 

 talline texture, both large grained and fine. This rock has been 

 improperly called green stone, and green stone syenite, the mis- 

 apprehension arising from its color. It is of very common occur- 

 rence. 



In some pieces I found at Kulhutty on my way up the Ghaut, 

 Cinnamon stone, and Smaragdite occur, garnets are also found 

 embedded. 



The rounded summits of the Hills in the neighbourhood of Oo- 

 tacamund, are occasioned by the concentric exfoliation of this rock, 



