sideration of that formation, commercially most valuable, and geologically most interesting, the Northampton Sand.
The main feature of my Second Part will be the description and consideration of a series of beds grouped by Mr. Judd under the name of the " Lincolnshire Limestone" — of less commercial value than the former, it is true, but scarcely of less geological interest.
My endeavour has been to trace, through the county in a north- easterly direction, to Stamford and somewhat beyond, the continuity of beds occurring in the Northampton district; to describe the Oolitic beds and their sequence at certain points within the area considered (involving the interposition of a new and important formation) ; to examine the geological characteristics of the districts round Stamford, and very briefly those of the eastern portion of the southern border of the county ; and thus, while giving a general idea of the geology of the Northern Division of Northamptonshire, to help to establish the soundness of certain views not yet held to be altogether conclusive.
My data were gathered and this Memoir was drafted before I had the advantage of examining Mr. Judd's Geological Survey Map, Sheet 64 ; while, unfortunately for geological science, but perhaps as well for the object I have in view, that gentleman's Memoir has not yet become the property of the public.
It may perhaps by some be deemed superfluous in me to have produced this treatise at all, seeing that Mr. Judd's map is already in the hands of geologists, and that his Memoir will shortly be published.
But some geologists still hesitate to accept the dictum that the beds of the Lincolnshire Limestone are Inferior Oolite ; and, as Mr. Judd, after some years of close and systematic examination of those beds, and I, after a less systematic and exact although longer acquaintance with them, have independently come to the same conviction upon this point, I have thought that my second voice might not be without service, nor my local information without interest — especially as I have come armed from the beds to be discussed with an array of significant fossils, those once animate though now inanimate " oldest inhabitants," those silent yet eloquent witnesses to the truth of the conclusions at which we have arrived.
Before entering upon the task I have essayed to accomplish, as the Northampton district will, as it were, form my starting-point in tracing out the extension eastwards of the Oolitic beds of that district, it will be well to recall to notice the General Section given in my former communication.
It will be seen by this diagram that upon the clay of the Upper Lias are superimposed the series of beds of the Northampton Sand, having a maximum thickness of about 80 feet ; which beds were divided by me (because of certain distinguishable characteristics) into " Lower," " Middle," and " Upper ;" that upon the summit of the Northampton Sand occurs a plane of unconformity, indicated in the diagram as the " Place of the Great Limestone of the Inferior Oolite" (the Lincolnshire Limestone of Mr. Judd) ; and that above
