Outcrop Line Research Articles

The Melbourn Rock and the Zone of Belemnitella plena from Cambridge to the Chiltern Hills

The Melbourn Rock was described by one of us in 1880 as a band of rocky chalk occurring in Cambridgeshire at a distance of about 80 feet above the Totternhoe Stone, and forming the base of a middle division of the chalk. Since then the outcrop of this rock has been traced south-westward through the counties of Hertford, Bedford, Buckingham, and Oxford, and has been found to be remarkably constant in its character and behaviour. It is generally found at the top of a well-marked feature or slope, and where it recedes into coombes, these are generally steep-sided; at the head of such valleys there are frequently powerful springs, which are thrown out by the marly beds at the base of the rock, so that it is of practical importance as a water-bearing stratum. While one of us has been engaged in drawing this line of outcrop for the Geological Survey and in noting the exposures along its course, the other has carefully compared these sections, as they were discovered, with those previously described in Cambridgeshire, has collected such ibssils as were to be found, and has cut and examined under the microscope numerous slices from the different beds of rock and from the chalk below and above. In the present communication, therefore, we propose to offer the results of our combined observations on this rocky band and the beds associated with it ; and for permission to make use of the information gained during the official survey of the

IX.—On the Geology of the Færöe Islands

In this paper I give an account of observations made during a visit in 1879 to the Færöe Islands in company with my friend Mr Amund Helland of Christiania. The principal object of our journey was to examine the glacial phenomena of the islands, but we studied so far as we could the various rockmasses of which the group is composed, and constructed a geological sketchmap to show the line of outcrop of coal, the disposition of the strata, the direction of dykes, and the trend of the glaciation. I have only to add, that all the observations recorded in the following pages were made in concert with my friend, and I am glad to say that we were quite at one in our general conclusions.

On the Intrusive Character of the Whin Sill of Northumberland

1. Introduction .—The basaltic rocks of the north of England occur in two forms—as sheets lying amongst the sedimentary strata, and as dykes cutting through them. The intrusive character of the latter is, of course, undisputed; but there is much uncertainty in the minds of many geologists as to the character of the former. In this paper we purpose to show, from the detailed work of the Geological Survey, that in Northumberland there can be no doubt whatever as to the intrusive nature of the bed or beds of basalt known as the Whin Sill. This conclusion can be established both by the evidence of individual sections and by the line of outcrop of the trap. The question of the nature of the Whin Sill is of importance in three ways:—1st, as a point of theoretical geology, bearing upon the history of volcanic action in Britain; 2nd, in reference to the classification of the Carboniferous System; 3rd, in its bearing upon practical mining. The Whin Sill is best known in Teesdale, especially in the two fine waterfalls of High Force and Cauldron Snout. It also appears along the face of the Penine escarpment, and is beautifully exposed in the “Nicks” which furrow the face of that range. Although this district is known to us, we will not stay to describe it, because it has already much engaged the attention of geologists, especially Professors Sedgwick and Phillips. It is generally supposed that there is but little evidence of intrusion there; but this

On the Structure of the Strata between the London Clay and the Chalk in the London and Hampshire Tertiary Systems

The preceding descriptions I believe embrace, with two or three exceptions, all the principal sections exhibiting the superposition of the basement bed of the London clay. Although, considering the extent of the line of outcrop, they are not very numerous, the intervals between them are sufficiently short to trace this deposit from place to place with considerable certainty. The details of each may vary in a few points, but they all present a general resemblance. This may not however be considered sufficient for our object—such thin and ordinary beds might be subordinate to some other portion of the Eocene series, and not peculiar to this part of them, and therefore some other proofs of their position may be thought necessary. In the first place, all the sections in the tertiary district show, by evidence of the clearest kind, that the London clay forms a nearly homogeneous mass, several hundred feet thick, of tough clay of a predominating brown colour—that throughout its whole body it nowhere presents any subordinate beds of a mineral character essentially different from that of its ordinary argillaceous type—and that its organic remains are very irregularly dispersed, abounding.in some parts and being entirely wanting in others. This clay occupies an area which is very well defined. Now wherever, without a single exception that I am aware of, the lower beds of this clay outcrop, there is found underlying them a basement bed of a conglomerate character and with or without organic remains—and these, if present, invariably belong