NOTES AND QUERIES. 
39 
instance, with the exception of the Northamptonshire beds, wliich have 
been carefully noted by my friend, the Hev, A. K". Griesbacli, I have 
visited the localities given in this work," but in no part of that mono- 
graph has my friend referred the Northampton Sands to the lias. Mr. 
Macalister has been therefore altogether misinformed on this subject. 
I submit that it ought to be a rule with gentlemen furnishing papers to 
the valuable pages of the ' Geologist,' in every case to refer to the original 
articles from which they quote. Yours most truly, 
Thomas Weight. 
Cheltenham, November, 1861. 
NOTES AND QUERIES. 
Subdivisions of the Chalk Formation. — The generally accepted 
subdivisions of the chalk are,— 1, Upper White Chalk with bands of Flint 
nodules ; 2, Middle or Lower White Chalk ; 3, Grey Chalk or Chalk 
Marl. 
These have been in undisputed use for very many years, not because they 
do not require any modification to render the accordance more definite and 
more rigidly corresponding to the accumulation of information which has 
been going on since their introduction, but chiefly because chalk, — at least 
English chalk, — is white or of a pale grey, which when the beds are in a 
dry state is so nearly white, that ordinary eyes do not see the difference, 
and ordinary collectors do not care about it so long as they can get hold of 
a fine fossil. 
Still, however, it is very necessary, and high time that some one should 
take in hand to define accurately the lines of division, especially that be- 
tween the upper and lower white chalks. 
I doubt very much that the cessation of the bands of flints denotes the 
demarcation between the upper and lower white chalk (middle chalk of 
some authors) : they should be properly, and must be ultimately, separated 
by a characteristic difference in the distinguishing organic remains. 
With the lowermost bands of flints (Plate II. a) very numerous beds of 
ventriculites and sponges set in, and are continued far below the termina- 
tion of the layers of flints, down to a very thick bed of pure white chalk 
{h), that rests upon a very marked and peculiar stratum about two feet 
thick (c), which, from the weathering out of its upper and under surfaces, 
forms a marked line as far as the eye can see the distinctions of bedding 
all along the coast. 
This bed, in my own note-books and in conversation, I have familiarly 
termed the " two-foot stratum." 
Below this we have again a thick bed of white chalk, free from flints. At 
least, such is the order in the section to -which these remarks more particu- 
larly refer, namely, that presented by the East or Castle Cliff at Dover, 
of ^^ hich we give a view in Plate II. 
This "two-foot stratum " is persistent throughout Kent, and I have met 
with it both in Surrey and Sussex, and it will therefore probably form one 
of the best and most unmistakable guides in inland quarries to those 
particular beds of white chalk to which we wish to draw attention, for the 
purpose of getting all the information we can as to their geographical area, 
order of succession, and organic contents in other chalk districts, so that 
the true horizon of division, as formed by distinctiveness of organic remains, 
may be properly made out. 
