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Published online by Cambridge University Press: 01 May 2009
In the August number of this Magazine, Mr. Howorth has challenged the view which I have advanced of the origin of the Loess (in common with the intrusive cave earth, the Warp of Trimmer, and the Trail of Fisher), from the slide of the upper and annually thawing layer of the permanently frozen soil, in the parts beyond the limit of the land-ice during the major and minor glaciations; or, as regards areas covered with sea during the major, from this process during the minor glaciation only.
page 392 note 1 Although the evidence of the minor glaciation in the Western States seems ample, yet Prof. Dana says that no sufficient evidence of it has yet been detected in the Atlantic States of the Union. It seems to me, however, that the “till-like deposit,” c g of the section at p. 182 of his paper in the American Journal of Science for March, 1882, shown as wrapping uncouformably the stratified sand which was deposited in the Connecticut Valley by the flood which resulted from the melting of the ice of the major glaciation. during the wane of that glaciation, affords such evidence. The Hessle clay of Yorkshire wraps thus unconformably the sand and gravel of the Cyrena formation; and its boulders are, like those of this bed e g, of the “Cobble-stone” character, and small in comparison with those of the clay of the major glaciation. As the less volume of the ice of the minor glaciation from which the Hessle clay originated, instead of so greatly overwhelming the valley partings as that of the major did, passed through the middle part of the Vale of York to the sea, so may the ice of the minor glaciation originating on the mountains of xSew England have been insufficient so to overwhelm the partings of the New England valleys, as that of the great glaciation did, but have escaped to the sea down those valleys, and there left its moraine on the sands which had previously been deposited there.
page 394 note 1 In the section of the Trowbridge railway cutting at page 719 of the second part of my Newer Pliocene memoir (Quart. Journ. Geol. Soc. vol. xxxviii.) reproduced from a paper by Mr. Mantell, the loam (Drift) with Elephant teeth (7 of my memoir) which 1 refer to this sliding origin during the minor glaciation is shown as not only enveloping the Jurassic formations of the hill through which the cutting was made, but as spreading over the gravel of the river Biss.
page 396 note 1 These are said (by Todd and by Broadhead) to occur also in the American Loess, though (according to the former) restricted to the upper 30 or 40 feet.