GLACIAL FORMATIONS IN ENGLAND.

Figure 38. Dome-shaped Rocks

  (FIGURE 38. DOME-SHAPED ROCKS, OR "ROCHES MOUTONEES," IN THE VALLEY
  OF THE ROTHAY, NEAR AMBLESIDE, FROM A DRAWING BY E. HULL, F.G.S.*
   (* "Edinburgh New Philosophical Journal" volume 11 Plate 1 page 31
     1860.))

The mountains of Cumberland and Westmorland, and the English lake district, afford equally unequivocal vestiges of ice-action not only in the form of polished and grooved surfaces, but also of those rounded bosses before mentioned as being so abundant in the Alpine valleys of Switzerland, where glaciers exist, or have existed. Mr. Hall has lately published a faithful account of these phenomena, and has given a representation of some of the English "roches moutonnees," which precisely resemble hundreds of dome-shaped protuberances in North Wales, Sweden, and North America.*

     (* Hull, "Edinburgh New Philosophical Journal" July 1860.)

The marks of glaciation on the rocks, and the transportation of erratics from Cumberland to the eastward, have been traced by Professor Phillips over a large part of Yorkshire, extending to a height of 1500 feet above the sea; and similar northern drift has been observed in Lancashire, Cheshire, Derbyshire, Shropshire, Staffordshire, and Worcestershire. It is rare to find marine shells, except at heights of 200 or 300 feet; but a few instances of their occurrence have been noticed, especially of Turritella communis (a gregarious shell), far in the interior, at elevations of 500 feet, and even of 700 in Derbyshire, and some adjacent counties, as I learn from Mr. Binney and Mr. Prestwich.

Such instances are of no small theoretical interest, as enabling us to account for the scattering of large erratic blocks at equal or much greater elevations, over a large part of the northern and midland counties, such as could only have been conveyed to their present sites by floating ice. Of this nature, among others, is a remarkable angular block of syenitic greenstone, 4 1/2 feet by 4 feet square, and 2 feet thick, which Mr. Darwin describes as lying on the summit of Ashley Heath, in Staffordshire, 803 feet above the sea, resting on New Red Sandstone.*

     (* Ancient Glaciers of Caernarvonshire, "Philosophical
     Magazine" series 3, 21 page 180.)