266 S. H. Howorth—A Great Post- Glacial Flood. 



At the present time there is an excellent example to be seen in 

 Earle Road, Smithdown Eoad, Liverpool, next to the site of a new 

 Board School that I am, as architect, superintending. The surface of 

 the ground slopes rather quickly to the valley below, and the super- 

 ficial strata consist of soil and a yellow subaerial quartzose sand, 

 together from 4 to 5 feet deep, in which there are no stones or gravel.-^ 

 This sand we are using for mortar, it being what is called " sharp," 

 or consisting of angular grains. Below this the corrugations of the 

 Boulder-clay are better developed than I have seen elsewhere, and 

 give a clue to the origin of these channel-like depressions. They 

 have just been cleared of the infilling, consisting of dirty clayey sand, 

 gravel and stones, and their structure is clearly displayed. They 

 are on the average about four feet wide, and three feet deep, but one 

 reaches to over eight feet wide, and they wind about in the most 

 indescribable fashion, but none of them have any outlet that I could 

 discover, nor are they all connected. The sides of some of these 

 channels slojje on one side and are undercut on the other, that is, 

 the clay overhangs the channel on one side. A few small boulders 

 were included in the sand infilling. 



The explanation of these curious channels appears to me to be 

 this : they are cracks or shrinkages in the Boulder-clay widened by 

 the constant very slow percolation of water — a somewhat parallel 

 phenomenon to the " pipes " in chalk. The clay at the sides of 

 the channels is quite yellow from the deposit of ochre washed out of 

 the sand above. The gravel and stones are the undissolved portions 

 of the Boulder-clay. 



V. — Traces of a Great Post-Glacial Flood. 



II. Evidence of the Loams and Brick-earths. 



By H. H. HowoRTH, F.S.A. 



{Continued from p. 231.) 



IF we now turn further east to Belgium and its borders, we 

 shall find the same conclusion arrived at by inquirers. In the 

 admirable memoir of M. d'Acy, already named, entitled " Limon des 

 Plateaux du Nord de la France," the author has examined in great 

 detail and with care the composition of the loamy mantle that 

 overspreads the other surface deposits of Belgium and Picardy. 

 His sections and descriptions show very clearly how its texture, 

 passing from coarse materials in its bottom layers and gradually 

 getting finer and more pulverulent in its upper ones, is such as 

 we should expect from the effect of gravitation acting upon great 

 masses of mud, etc., borne along by a rapid flood. And where 

 the Jimon unites with the subjacent beds in situ, we see how the 

 surface of the latter has been ploughed and eaten into in a most 

 remarkable way, the Umon filling up the hollows and holes torn in 

 its surface as we should exactly expect, I will now quote a sentence 

 or two from this work. He speaks of this Post-Glacial deposit, 



' This formation I have called "Washed drift sand." See " Post-Glacial Geology 

 of the Mersey Estuary," Geol. Mag. 1872, p. 113. 



