IXX PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 18995 



Reservoir (for Sheffield), where Boulder Clay made a more or less 

 water-tight bottom, and another (Yarrow Eeservoir, Eivington) 

 where Drift (sand, gravel, Boulder Clay, and loam) filled up a deep 

 pre-Glacial valley and caused much difficulty. 



Tracts in which there are large landslips are clearly dangerous ; 

 for, with rocks as with men, where a slip has occurred, there 

 another is likely to happen some day, as witness the Sandgate 

 landslip of 1893, which was within the area of an older slip. 

 Moreover, the process of cutting into a slipped mass of rock and 

 earth is likely to start fresh slips, and to endanger the stability of 

 the work. An instance of this may be given from the Manchester 

 Waterworks in the Yalley of the Etherow, several miles east of 

 the city, made many years ago, when the characteristics of old 

 landslipped tracts were not so well recognized as now. The lower 

 part of the deep valley along which the set of reservoirs has been 

 made is in Millstone Grit ; but, above this, the part in which most 

 of them are placed has been cut through the Millstone Grit to the 

 Yoredale Beds, especially on the southern side. The Yoredale Beds 

 being largely composed of shale, the conditions are favourable to 

 springs and slips, and, as noted on the Geological Survey map 

 (Sheet 88, S.E.), the greater part of the southern side of the valley 

 is a landslip-area. The features of this are very clear, especially in 

 the neighbourhood of the Woodhead Eeservoir, the highest of the 

 series, the dam of which impinges on the landslip, by Crowden 

 Station. Under these circumstances, one is not surprised to hear 

 that this reservoir was, for some years, never filled to within 15 or 

 20 feet of its height, because it was thought unsafe to fill it, owing 

 to a landslip and to the unsoundness of the embankment, until a 

 new embankment had been made. I understand, indeed, that the 

 dam is now practically double. 



In the above remarks I am not finding fault with this fine set of 

 works, but only showing how difficulties, of a nature that a geologist 

 would expect, interfered with the plans of so good an engineer as 

 the late Mr. Bateman. I am inclined to think, indeed, that old 

 landslips are more common than most geologists suppose. In my 

 Geological Survey work in Hampshire I found that the right, 

 or western, bank of the Test, near Eomsey, was for a long distance 

 a great slip, with the usual irregular features ; and later on the 

 same was found to be the case with the left, or eastern, bank of 

 the Itchen, opposite Southampton. In both cases no beds in place 

 could be seen, except the gravel at the top. So far as I know, these 

 two occurrences had never been noticed ; but many others have 



