THE WEST OF ENGLAND AND EAST OF WALES. 451 
west plain would appear to be alone, or almost alone, represented. 
The comparative, if not entire, absence of subglacial mud from the 
Lake-district beyond this waterparting (the Severn valley perhaps 
excepted) has probably been compensated by the prevalence of Car- 
boniferous, Permian, Triassic, and Liassic shale, marl, or clay, out 
of-which deposits of clay or loam have been locally worked up. The 
same kind of boulders occur in this local clay as are found in the lower 
glacial clay of the north-west ; and they must have been transported 
and precipitated during the same submergence. The clay around 
Wolverhampton and Stafford, as shown in numerous clay-pits, is 
very seldom underlain by sand, excepting where there has been a 
working up of sandstone rock underneath*. There are no clear 
traces (so far as I have seen) of two Boulder-clays in this district, 
though sometimes it might be easy to fancy so, because the boulder- 
bearing clay graduates into sand, loam, and gravel at different levels, 
though still on the same horizon; in other words, it changes with 
changes in the character of the underlying or neighbouring strata, 
In the clay-pits around Wolverhampton and Stafford northern 
boulders are found at various levels in the clay, but mainly in the 
upper part near to or on the surface, as if a part of the clay (at 
least in certain areas) had been deposited before the submergence 
became sufficiently deep to float boulder-laden ice over the above- 
mentioned waterparting. At Ashfiat clay-pits (south of Stafford) 
the clay, with many northern erratics, is overlain by gravel and 
sand which have evidently been washed out of the clay—the junc- 
tion between the two being very uneven, generally ill-defined, and 
often presenting the appearance of “pipes.” Fine gravel may be 
seen in Wobaston Big Meadow, further south, and I believe it is 
underlain by boulder-loam. Most of the large boulders between 
Wolverhampton and Bridgenorth would appear to be imbedded 
either in clay or in gravel with a matrix of clay graduating into 
sand. Most of the boulders which have been removed from the 
fields were found partly, or almost wholly, above the surface, or not 
so deeply buried as to elude their being touched by the plough. At 
first 1 was deceived by fancying that the occasional occurrence of 
vertical and, to some extent, grey-faced partings in the clay around 
Wolverhampton was sufficient to correlate it with the upper clay of 
the north-west; but I soon found that it was only an accidental 
resemblance, and that the structure of the two clays was different, 
the Wolverhampton clay being more or less heterogeneous and inco- 
herent, while the upper clay of the north-west is remarkably homo- 
geneous, tenacious, and compact, characteristics which cause it to 
slide one portion on another when damp, and when dry to break up 
in large columnar masses instead of frittering away. 
* Tn the neighbourhood of Birmingham, sand sometimes comes under a loamy 
clay or gravel; but whether it be a local variation on the same horizon, or a 
westerly representative of Mr. 8. V. Wood’s Middle Glacial Sand of the eastern 
counties, I have not had time to ascertain. It ought to be recollected that under 
the Lower Boulder-clay of the north-west plain there are occasionally sands of 
local derivation. 
