THE GEOLOGICAL AGE OF CENTRAL AND WEST CORNWALL. 195 



across the river to Victoria Point near Malpas (21), while 

 another, apparently the main mass, appears in a field at the 

 head of Lamb Creek, and then skirts the creek itself on the 

 western side for a considerable distance (22). 



Near Malpas (21) three separate veins or branches are 

 visible at low water, one of these disappears beneath the 

 slate in a quarry near the shore. 



Nos. 20, 21, and 22 are not marked on the survey map. 

 Mr. Barnett in his description speaks of the " elvan " as " lying 

 conformable with the slate " at Channel Creek, but a close 

 inspection shews that this is not exactly the case. On the south 

 side of the creek, the killas is seen to dip at a greater angle 

 than the dyke. It is here of a grey colour and dips about 25"^ 

 from the horizontal, while the principal dyke is inclined not 

 more than 17°. It is here about 30 feet thick, and has a very 

 decided concretionary or rather spheroidal structure. This 

 indeed is more or less observable wherever it is exposed to any 

 considerable extent. On the north side of Channel Creek the 

 dyke is smaller — it has about the same inclination as before, but 

 but the killas is here much more nearly horizontal, as shewn in 

 the sketch fig 3 — so that here it is clearly intrusive. 



C/tannel Creek 

 N. Side. 



In the creek to the north of Eoundwood the killas dips about 

 43° to the S.S.E., while the dip of the dyke is about 25°. 

 Above the dyke the killas is much contorted, as shewn in the 

 sketch fig 4. 



Fig 4. — Creek tiear Roundzvood. 



Near this place, too, we found the trap faulted as shewn in 

 the sketch fig 5. The killas was lent into the angles and not 

 broken. A good deal of carbonate of lime existed here in the 

 joints. 



M 



