239 
Correspondence — E. Wilson. 
my intention to refer to, but not to sanction tbis idea, as an impartial 
critic will, I think, readily perceive. To speak candidly, these beds 
require furtker study before tbeir precise relationskip can be satis- 
factorily determined. 
While by no means prepared to affirm that “ a perfect conformity 
exists between the Magnesian Limestone and the New Red (meaning 
Bunter) Sandstone in the N.E. of England.” I dilfer widely from 
Mr. A veline, in bis view tbat tkere is proof of a great break between 
these formations. In Support of this position, he cites the successive 
overlaps of the Upper Permian Marls and Limestone, Middle Marls 
and Lower Limestone, by the Bunter Sandstone, going south, from 
the district north of Worksop, to the latitude of Nottingham. 
But has it ever occurred to him that all these cases may be of the 
nature of oonformable overlaps ? My own experience of the Marl 
Slate, Lower Magnesian Limestone, and Middle Marls of this dis- 
trict, founded on accumulated data, not attainable in Mr. Aveline’s 
time, convinces me that there is a general tendency in these sub- 
formations to attenuate inter se, as also to become coarser in texture, 
when followed from the north or north-east towards the south or 
south-west. To eite one or two instances of this. The attenuating 
Lower Magnesian Limestone, which, for the last few miles of its 
Southern extension, has become in great part a flaggy, sandy, and 
even conglomeratic rock, dies out as a coarse brecciated littoral 
deposit. The Middle Marls 1 have just previously faded away. 
Simultaneously, the Marl Slate series has diminished from 60 or 70 
feet of shales (mostly), to 20 feet of sandstones (mostly), and from 
that to nil, when the basal Permian, a coarse brecciated rock, comes 
directly beneath the last degraded relic of the Magnesian Limestone. 2 
These facts in my opinion point to the existence of an inter-Permian 
marginal barrier immediately to the south, and somewhat more 
remotely to the west, and to successive synchronous increments of 
subsidence in the opposite directions. 
I do not believe that any of the above rock series ever 
stretched appreciably further south than they do now. Extending 
this reasoning to the Upper Magnesian Limestone and uppermost 
Permian Marls (as to which my data is admittedly more limited), 
I would suggest that they never extended appreciably further south 
than they respectively do now, and that their soutkerly disappear- 
ance is due to analogous causes. Successive increments of subsidence 
in a north-easterly direction will account for these phenomena. 
Inter-Bunter-Permian denudations will not. Small local irregu- 
larities undoubtedly exist between the Lower Bunter and (the 
1 The persistent outcrop of this thin and denudable series between the Mag- 
nesian Limestone and Lower Bunter formations negatives the idea of any great 
amount of denudation between these two periods in this neighbourhood. 
2 It thus appears that tbe Magnesian Limestone overlaps its own Marl Slate base, 
with which it appears to be perfectly conformable. Tet no one supposes there is a 
*• great break ” between them. Had, however, this overlap been concealed by a cloak of 
Lower Bunter, that formation, and not the Magnesian Limestone, would have been 
credited therewith, and the fact cited as an additional proof of the great break 
between the Permian and New l<ed Sandstone periods. 
