368 SKY. GEOLOGY. OVERLYING ROCKS. 



to be placed in a disorderly manner, or are mixed together 

 in a kind of lateral alternation. In this way, common 

 greenstone, amygdaloidal claystone, common pale syenite, 

 micaceous syenite, and simple blue claystone, will be 

 found irregularly recurring throughout the whole group ; 

 which in the map is marked by one colour only, since 

 any topographic distinction of these variations was impos- 

 sible. It may nevertheless be added, that syenite under 

 different aspects is by far the predominant rock through- 

 out this region. The hill of Glamich may be quoted 

 as an example of these transitions and mixtures ; since 

 it is unnecessary to accumulate instances where few will 

 be inclined to examine them. They are however not 

 unfrequent in that part of the island which is the common 

 boundary of the syenitic mountainous region and the 

 lower country of hilly or of stratified trap ; and they may 

 very conveniently be examined at Loch Sligachan, as 

 well as on the shores of the eastern Loch Eynort and of 

 the sound of Scalpa. 



A question will naturally arise here ; namely, whether 

 there is any difference of age between the several rocks 

 of the unstratified division; whether for example the 

 syenite is of prior or posterior origin to the ordinary trap 

 rocks or to the hypersthene rock of the Cuchullin. If 

 that which is just related respecting the interchanges of 

 the two former be correct, there is no reason to imagine 

 any such differences to exist. Still however, certain por- 

 tions are to be seen which appear posterior to the main 

 body of stratified trap, and consequently to the syenite ; 

 the reasons for which opinion will be better introduced 

 when these shall hereafter come under review. If there be 

 any such difference between the syenite and the rock of the 

 Cuchullin there appears no great prospect of discovering 

 it. Although the former is found within a short distance 

 of the latter, the intermediate space scarcely admits of 

 the necessary examination, nor can the connexion be 

 traced more circuitously through the intervention of the 



