Northampton Sands.
Dear Sir,—In replying to Dr. Wright's communication in the last number of your excellent periodical, I offer him my apologies. The origin of my mistake was, in carelessly reading that part of Mr. Aveline's 'Memoir on the Geological Survey of a part of Northamptonshire,' where he speaks of the confusion that formerly existed with regard to these sands.
These beds have been assigned to the Upper Lias, although not by Dr. Wright, and are so coloured on more than one geological map. For instance, in Reynolds's 'Geological Atlas,' lately published under the revision of Professor Morris, all the country over which the Northampton sands are so well displayed has been coloured, with the Lias, brown, a mistake which should be avoided if a second edition of that neat and otherwise useful little work is contemplated.
The fact is, no one knows exactly where to place or with what to class these sands. Lias they assuredly are not. Mr. Aveline considers them to be equivalent to the Stonesfield Slate of Oxfordshire. This seems likely, both from their position and their organic remains. But a deal yet remains to be done with them; they have yet to be accurately traced, searched, and studied. Strata which yield, as they do, such valuable iron-ore, demand attention and examination.
Yours very truly,