64 WYNNE: GEOLOGY OF KTJTCH. [PAET I. 



in the adjacent underlying rocks, it seems safer to adopt this view rather 

 than the sub-aerial theory involving operations so different from those 

 resulting in the terrestrial volcanic phenomena of the present period. 



Inteusive Traps. 



The very numerous trappean intrusions of Kuteh are almost 

 Intrusions confined to entirely confined to the Jurassic area. Their 

 Jurassic aiea. general similarity and extensive distribution shows 



their source beneath the whole area to have been extensive ; and their 

 frequent identity with the overlying stratified trap, in numerous cases 

 difiering only in the absence of stratification, leaves little doubt, if any, 

 that the superincumbent flows found their way to the surface through 

 similar channels; many of these intrusions marking absolutely passages 

 through which they rose. 



They include nearly all varieties of doleritic, traehytic and basaltic 

 traps, crystalline, compact, or porphyritic, seldom 



Varieties. , , ■ , , 



amygdaloidal, sometimes columnar, and frequently 

 so friable and disposed to weather away that no clean fracture can be 

 obtained. Some lavender or purple and red earthy lava dykes and pockets 



occur by themselves or associated with the other 



PurT)l6« 



intrusions. From their resemblance to certain 

 beds or flows overlying the rest of the stratified traps, they are supposed 

 to have formed some of the latest eruptions. 



The larger intrusive masses which will be found marked upon the 

 map, forming considerable sized hill ranges, are all 

 of a coarsely crystalline doleritic variety, which 

 assumes under the influence of the weather the massive form and external 

 appearance of iron-stained syenite. These intrusions penetrate the 

 rocks in the most complex manner, some hills being a tangled net- 

 work of dykes and intrusions embracing large masses of the associated 

 ( 64 ) 



