248 Proceedings of the Royal Physical Society. 



the Lutje Berg and the Nordberg. For a distance of about 

 100 yards, the shales which dip S.E. at about 30° are cut 

 across and sometimes completely surrounded by the diabase, 

 dykes and stock-like masses of which rise vertically or 

 diagonally through them, sending out " apophysen " and 

 hardening the strata at the contact edges. 



The accompanying sketch section (Fig. 1) shows the re- 

 lation of the diabase to the shales at one of the most charac- 

 teristic parts of the exposure. Murchison and Sedgwick also 

 give a section in which the diabase is seen rising vertically 

 through the shales of the N'ordberg. The shales are slightly 

 inclined, and are here as on some parts of the Steinberg 

 cleaved and converted into good roofing slates, which are 

 largely quarried at different places round the base of the 

 hills. 



Another section of intrusive diabase is seen at the Teufels 

 Ecke in the Innerste Valley below Lautenthal, at a point 

 where the road has been cut into the Upper Devonian 

 Kramenzelkalk beds to make room for the railway. The 

 diabase is here very pyritous and weathers brown with a 

 yellow efflorescence. It runs through the Devonian beds in 

 veins whose presence can sometimes only be detected on 

 careful inspection, as they are often not more than one or 

 two inches in thickness. The whole section is about 20 

 yards in length. 



The last case of intrusive diabase to be noticed is at the 

 locality already referred to about 3 J kilos S.E. from Clausthal, 

 where a good section of the overlying contemporaneous 

 diabase is exposed in a stream entering the Hutthal. At the 

 top of this tributary valley diabase veins are seen rising 

 through the Goslar shales, which are here, as on the Konigs- 

 berg, exposed in a small roadside cutting, and are inclined at 

 a high angle. At some parts of the section the massive rock 

 is in veins parallel to the bedding of the shales, but at others 

 it is distinctly unconformable, and hardens the shales through 

 which it passes. In all cases the edges are quite sharp, and 

 not rough or slaggy. 



It is probable that these diabases were irregularly injected 

 into the underlying rocks, at the same time that the others 



