On the Wenlock Shales of the Welsh Borderland. 



i27 



The results obtained by the author completely confirm the work 

 of Tullberg on the Wenlock Shales of Southern Sweden. 



Along the Welsh Border the Wenlock rocks do not cover a large 

 area, but are merely a fringe to the Ludlow rocks. The former 

 are characterized by graptolites of the priodon- Flemingii type, the 

 latter by those of the colonus-type. 



The general structure of the Builth district is a syncline towards 

 the north and north-west, part of a series of folds whose axes 

 run north-east and south-west. A later set of movements, along 

 east-and-west axes, and of later date, lifted the district to the 

 north and north-west of Builth, and, combined with the effect of 

 previous movements and subsequent denudation, caused the exposure 

 in the north and north-west of beds which are overlapped to the 

 east. The full six zones in the foregoing table occur to the north- 

 east of Builth-Eoad Station, but some of them are overlapped 

 north-west of Builth ; and at Aberedw Hill, east of Builth, only the 

 highest zone is exposed. The entire succession in the northern and 

 north-western part of the district is given below : — 



