Erratic blocks of England and Wales

Thanks to Rob for drawing my attention to this wonderful article and map.  I had never seen this info before.  It has come to the surface thanks to the great project under way in the Birmingham area, in which Rob and Prof Ian Fairchild are involved.

Look at the date of this work: 1878.  That's rather a long time ago.  But our Victorian ancestors were great field workers and often pretty good geologists too -- even though their ideas on glaciation were rather primitive, to say the least.  No matter -- the observations formed the foundations of much of the glacial history as we understand it today, and the maps are classics of their kind.

I particularly love this bit:  "There are probably many boulders which I have not yet seen, and the positions of which, therefore, are not shown in the map."  Quite so.

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Thanks to the wonders of OCR, here is a transcript of part of the paper:


ERRATIC BLOCKS OF ENGLAND AND WALES. p 425

RESULTS of a Systematic SURVEY, in 1878, of the DIRECTIONS and Limits of DISPERSION, MODE of OCCURRENCE,and RELATION to DRIFT-DEP0SlTS of the ERRATIC BLOCKS or BOULDERS of the West of ENGLAND and East of WALES, including  a REVISlON of many Years' previous 0BSERVATIONS.

By D. MACKINT0SH, Esq., F.G.S. (Read March 26, 1879.)


Extract
IX. :EXPLANATION OF MAP, PLATE XXlI.

As it is impossible to ascertain the precise routes taken by boulders, in a map it is perhaps least presumptuous to draw straight or slightly curved lines from their sources to their terminations. As most of the Kirkcudbrightshire granite blocks would appear to have been dispersed from Criffel mountain or the neighbourhood, to prevent complication I have represented that mountain as the centre of dispersion. The barrier offered by the westerly extension of the Cumberland mountains renders it necessary to assume a curve in the route taken by these boulders. As I have already described the Shapfell granite dispersion (see Geol. Mag. for Aug. 1870 ; and Quart. Journ. Geol. Soc. for Aug. 1873), and as it has been made the subject of papers by other authors, I have only mentioned it in the map. For the same reason the stream of large limestone boulders found along the east coast of Morecambe Bay is merely mentioned. The boulders of Silurian grit, felstone, &c. which went south from the mountain-front of Westmoreland are merely mentioned, as it is not certain that many of them found their way further south than Morecambe :Bay. The "greenstone" boulders are not inserted in the map. As the Arenig boulders which are believed to have wandered as far south as the neighbourhood of Bromsgrove would appear to have gone first in an easterly direction, it is obviously necessary that a curved route should be assigned to them in the middle part of their course. There are probably many boulders which I have not yet seen, and the positions of which, therefore, are not shown in the map.

An attempt to map the positions and courses of boulders is justified by the fact that most of them have been found more or less imbedded in clay or gravel, at all angles, often standing on end - in other words, in the positions in which they were left by the ice which carried them during the Glacial period.