In a glacial bed near Greenock, Mr. A. Bell found the fry of living Mediterranean forms, viz., _Conus Mediterraneus_ and _Cardita trapezia_.
Although deposits containing shells of a temperate or of a southern type in glacial beds have not been often recorded, it by no means follows that such deposits are actually of rare occurrence. That glacial beds should contain deposits indicating a temperate or a warm condition of climate is a thing so contrary to all preconceived opinions regarding the sequence of events during the glacial epoch, that most geologists, were they to meet with a shell of a southern type in one of those beds, would instantly come to the conclusion that its occurrence there was purely accidental, and would pay no special attention to the matter.
_Evidence derived from “Borings.”_—With the view of ascertaining if additional light would be cast on the sequence of events, during the formation of the boulder clay, by an examination of the journals of bores made through a great depth of surface deposits, I collected, during the summer of 1867, about two hundred and fifty such records, put down in all parts of the mining districts of Scotland. An examination of these bores shows most conclusively that the opinion that the boulder clay, or lower till, is one great undivided formation, is wholly erroneous.
These two hundred and fifty bores represent a total thickness of 21,348 feet, giving 86 feet as the mean thickness of the deposits passed through. Twenty of these have one boulder clay, with beds of stratified sand or gravel beneath the clay; twenty-five have _two_ boulder clays, with stratified beds of sand and gravel between; ten have _three_ boulder clays; one has _four_ boulder clays; two have _five_ boulder clays; and no one has fewer than _six_ separate masses of boulder clay, with stratified beds of sand and gravel between; sixteen have two or three separate boulder clays, differing altogether in colour and hardness, without any stratified beds between. We have, therefore, out of two hundred and fifty bores, seventy-five of them representing a condition of things wholly different from that exhibited to the geologist in ordinary sections.
The full details of the character of the deposits passed through by these bores, and their bearing on the history of the glacial epoch, have been given by Mr. James Bennie, in an interesting paper read before the Glasgow Geological Society,[125] to which I would refer all those interested in the subject of surface geology.