BASAL CAMBRIAN BOCKS OF SHBOl'SUIRE. 403 



chiastolizcd, and both are indurated. Below the falls there is 

 another mass of micaceous altered slate ; and irregularly related to 

 this is seen a mass of pyromeride on its western side. The igneous 

 rocks appear to have run in among the slates along their bedding, 

 and their flow-lines, like the crystals in many dykes, are naturally 

 parallel to the sides of the path. The whole of the grit that is seen 

 in lladlith is also very much altered. In any case the acid igneous rock 

 is in association here with purple slates and grits, which are recog- 

 nized as Cambrian. On the other, or eastern, side of the hill, the 

 associated slates and grits are of a different character. The area is 

 certainly a faulted one, and the unusual dip of the conglomerate and 

 grit may be thus accounted for, if the igneous rocks are of later 

 date. Ithyolite pebbles are doubtless found in the conglomerates, 

 but not abundantly, and they do not specially resemble and need 

 not have been derived from the rock here exposed. I can find, 

 therefore, no Archtcan rock here, but conclude we are altogether far 

 above the base even of the Cambrian. 



In the next locality referred to, near Gatten Lodge, there is nothing 

 very peculiar to be seen. The western side of the Lougmynd grit in 

 many parts of its range is marked by veins of baryta, sometimes 

 associated with copper, as at the old ^-orkings at AVestcot; and 

 (jiatten Lodge is a spot where these veins are abundant and have 

 been worked. Their presence indicates doubtless some disturbance, 

 and the grits do put on a very compact and irregular appearance ; but 

 under the microscope they are grits still, as will be seen by Prof. 

 Eonney's description of the rock submitted to him, and which I 

 entirely confirm. There is nothing Archiean here. 



The locality referred to as Knolls liidge and Cold Hill is par- 

 ticularly instructive (see fig. 2). On the north of the Farm of 

 Squilver commences an acid igneous rock, of rather varying cha- 

 racter, but mostly of grey felsite, which can be traced uninter- 

 ruptedly as far as Cold Hill Farm. At first it is in contact with 

 a bed of conglomerate ; a little further south there is a mass of grit 

 intervening in the valley-sides between the felsite ridge and the 

 conglomerate ridge, which come together again at the southern end. 

 The felsite ridge then leaves the conglomerate, and is separated 

 from it by a valley of pale slate. At Cold Hill Farm the con- 

 glomerates are seen dipping westerly at G0°. They are followed 

 by the pale slates seen in the road 1o dip at the same angle, and 

 further to the west comes the exposure of felsite. This proves that 

 the felsite ridge is transgressive across the edges of the strata, which 

 are here pretty nearly in their natural succession. This conclusion, 

 perhaps, is made more certain by the occurrence of two masses of 

 similar compact felsite in the heart of the Cambrian grits, as marked 

 on the map. Here, then, there is nothing Archaean. 



As we trace the pale slates to the south, we see them rise at last 

 into a conical elevation called Chittol Hill. Here they are more 

 compact and greener, and the bedding is somewhat difticult to make 

 out. They ai)pear to be not far from horizontal. The cause of 

 their elevation and compact appearance may be connected with some 



