Strata in the Brook Pulcovca. 
385 
The limestone again succeeds, at Mand (), above the dark clay, 
and dipping gently to the north-east. The cliff being much broken 
down between B and M, unfortunately prevents the discovery of 
the manner in which the limestone strata bend over the clay. This 
is the more to be regretted, as at n , where their junction is visible, 
it presents appearances well worthy of attention, and the cliff being 
also too low there to admit of our tracing the continuance of any of 
the limestone beds over those of the dark clay, their conformity 
appears almost doubtful. 
Hitherto, (and indeed every where below this spot,) the three 
strata, however bent and thrown out of their apparently natural 
position, have preserved a stratification conformable to each other, 
wherever they have been found in contact, and it is probable they 
have found means to preserve it even in the difficult situations 
between t and 0 , though concealed from our observation. But here, 
at n (PI. 25, fig. 1), the limestone in beds but slightly inclined, 
appears to abut abruptly against the beds of clay which are vertical, 
and even to join with it and pass into it as usual, gradually becoming 
a part of the same mass. It must be confessed, that at the place 
where the beds become green, the cubical fracture which charac- 
terises the limestone, renders it doubtful whether the strata are 
perpendicular with a horizontal cleavage, or horizontal with a 
perpendicular one ; at the distance of a foot on each side, their 
contrary stratification is perfectly evident. It may turn out that this 
cross cleavage is only the effect of a sudden turning up of the lime- 
stone, similar to that of the dark green clay close to it. If the bank 
had not unfortunately been broken down, the limestone beds might 
have been traced over this arch of black clay : that being no longer 
possible, the difficulty seems to admit of no solution, unless some 
analogous nonconformities of these strata be hereafter discovered \ 
3 c 3 
