ON THE ERRATIC BLOCKS OF ENGLAND, WALES, AND IRELAND. 137 



Silurian age, but whether from the interbedded volcanic rocks of the 

 Llandeilo or the Bala series I am not sure. One would expect them to 

 come from the Arenig district. I have seen nothing like them in the 

 Lake District.' 



Two of the felsites are of considerable size, the larger being 

 4x4x2 feet. 



Similar blocks may be traced almost to the summit of the hill. One 

 felsitic block opposite the Yew Trees is 4 - 5 x 3 X 2 feet. 



The height of these boulders above the sea is remarkable for the dis- 

 trict, their highest level being about 750 feet. This fact indicates a 

 corresponding depi'ession of the land, since no Welsh glacier could have 

 travelled over hill and down dale to this summit level. To render any- 

 such glacier work conceivable, the Welsh mountains must have stood at 

 a height beyond any point for which there is the slightest evidence. 



This group of boulders on the summit of Frankley Hill appears to 

 have been dropped by an iceberg travelling from Wales, upon the top of 

 the clays and sands exposed in the railway cutting, at a time when the 

 land was depressed at least to the extent of at least 800 to 1,000 feet. 

 In the clays and sands upon which the summit group of erratics rest, we 

 must have beds belonging to an earlier date than the close of the glacial 

 epoch, and the erratics in the cutting must be discriminated from those 

 left at the higher level. 



Staffordshire. — The following among the innumerable erratic blocks 

 scattered over the central part of the midland district deserve a special 

 record in addition to those described in previous Reports. 



1. A boulder of felsite in the brickyard at the bottom of Oak Street, 

 Wolverhampton. 



This boulder is of an oblong form, and measures 11x3x3 feet for a 

 considerable portion of its length, although tapering in a somewhat 

 irregular manner towards its ends. On the upper surface are rude and 

 rough groovings running in all directions, and doubtless produced by 

 the plough ; but one of the sides exposed is flat and smooth, and is 

 covered with parallel stria?, affording an extremely fine example of glacial 

 action. 



The clay by which it is surrounded contains many more or less 

 rounded pieces of granite, as well as of felsite, flints, together with 

 quartzite and other pebbles from the Biinter beds. 



The large felsite ice-marked boulder described was probably dropped 

 upon the clay in which it rests, this clay itself being composed of the 

 material brought by one of the earlier icebergs and intermixed with 

 material of more local origin by the currents prevalent during the move- 

 ments of the sea-bottom at a later period. 



In the immediate neighbourhood is a surface boulder of granite 

 measuring 3 x 35 X 2 feet. The grouping of these surface boulders needs 

 to be carefully observed, as distinguished from the accumulation of blocks 

 of all kinds, in the sands and clays upon which they rest, or into the 

 heart of which they have fallen. 



2. An erratic block of slate, situated in a field near the Fox Inn, on 

 the road to Trescott. 



This block has split into two pieces, the larger piece measuring 

 11-25 x 3-25x3-5 feet, and the smaller 9-25x3x3 feet. It originally 

 rested upon the surface, but some years ago it was buried, in order to 

 utilize the land for agricultural purposes. An excavation was recently 



