302 Mmo — Distribution of White Clays and Sands 



nished me by Mr. Blake, showing the contents of one of the pockets 

 and representing a section, as follows : — 



1st. Clayey Limestone-drift.... 27 feet. 



2nd. Soft Lignite ^. 1 foot. 



3rd, Brown, blue, or white clay, interstratified with a 



little fine sand and gravel about 31 feet. 



4th. Bluish sand, of unknown thickness 



59 feet. 



Details of Boring. 



Limestone-drift, gravel and sand, mixed with yellow clay 27 feet. 



Soft Lignite 1 foot. 



Tough brown clay, mixed with fine gravel 9 feet. 



Brown clay striped with blue 2 „ 



Brown clay with gravel 2 „ 



Sandy-grey clay 1 foot. 



Grey clay striped with blue 1 „ 



Sandy-blue clay 1 „ 



Fine blue clay 1 ,, 



Brown clay with fine gravel 2 feet. 



Fine blue clay 1 foot. 



Coarse brown clay ... 1 „ 



Blue clay with sandy veins 10 feet. 



69 feet. 



At a depth of 59 feet, blue sand, containing water, was reached, 

 when the boring was discontinued. 



The questions bearing on the foregoing facts that invite con- 

 sideration, relate 



1st. To the probable age of these deposits. 



2nd. As to whether they are the remnants of a more extensive 

 formation, that once spread over the whole of the districts in 

 which they occur, or are mere local deposits produced by 

 subaerial action, that never much exceeded their present 

 dimensions. 

 3rd. Eegarding the source of the component materials. 

 4th. As to the process of the excavation of the pockets and cavities 

 in the Mountain Limestone, in which the deposits are almost 

 invariably preserved. 

 With reference to age it would be unsafe to assume that these 

 similar deposits in Tipperary, North Wales, and the Midland Counties 

 of England, belong exclusively to the same geological period; and the 

 only fact that can be relied on is their unquestionable infraposition to 

 Boulder-clay drift, which holds good ia all the localities I have 

 examined in North Wales and Staffordshire, and seems, also, con- 

 stant with respect to the occurrence of the deposits of like mineral 

 character in Ireland : their similar position and physical resemblance 

 in all the localities is remarkable. Nearly all the examples occur 

 between the Boulder-clay drift and the Mountain Limestone, and in 

 nearly every case the same beds of peculiar mineral character are 

 associated. The soft chert breccias, white clays, dark laminated 

 clays, white sands, and carbonaceous beds, are recorded from widely 



