Correspondence — H. W. Bristow. 189 



(which I observed in December last, in the excavation for gas-works) 

 at Blowick, near Southport, one would expect varying and alternating 

 conditions, and contemporaneous " Lower Scrobicularia Clay " to 

 alternate, or even entirely take the place of the Lower Cyclas Clay, 

 in any local area. 



The following remarks occur in my paper on the "Post-Glacial 

 Deposits," etc. (describing the Leasowe Clays) : — " Whilst this 

 deposition went on, freshwater forms might have lived in pools of 

 fresh water in hollows of the Boulder-clay, simultaneously with 

 marine in other pools, filled by high tides a few feet distant ; — fluvia- 

 tile and marine forms of life preponderating horizontally and verti- 

 cally in the silts, according to whether freshets or spring tides 

 happened to be in the ascendent. This state of things is going on 

 at the present time, in the marshes of the Eibble, between Preston 

 and Southport, where, after heavy rains or floods, freshwater shells 

 may be found, during neap tides, in the hollows of the (recent) 

 Scrobicularia mud, and where crabs may be found living in all the 

 ditches for one or two miles inland." 



At the close of the Glacial epoch, several alternations of level 

 appear to have taken place ; the surface of the Upper Boulder-clay, 

 beneath the Shirdley Hill Sand, is coated with a thin seam of peat, 

 at a little above the present high-water level, formed after much 

 denudation of Boulder-clays in the lowlands had taken place. 

 Over this denuded plain of Boulder-clay the Sands were dejDosited, 

 and blown from its edges into a line of ancient dunes, equivalents in 

 time of the Presall shingle-beds (Quart. Journ. Geol. Soc, 1870, p. 461), 

 and the Eampside beds described by Miss Hodgson of Ulverstone. 



This sea-bottom becoming land, gradually increasing in extent, 

 streams cut channels in the sands, and carried their debris westwards, 

 into the hollows, and swamp basins, in the Boulder-clay, and deposited 

 the Cyclas Clay, which graduates westwards, along a line not exactly 

 corresponding to the present sea-coast, into the Lower Scrobicularia 



Elevation continuing with obstruction of drainage, peat was 

 formed, under continental conditions, which conditions are now being 

 succeeded by a subsidence still in progress. 



In the Blowick Clay, a skull and several antlers of Eed Deer have 

 been recently discovered at a depth of 16 feet from the surface. One 

 of the latter, procured by my friend the Eev. John Bone, of 

 Southport, has been presented by him to the Museum of Practical 

 Geology, Jermyn Street. 



I am glad to see that my suggestion to Mr. Eeade, of examining 

 the Grey Clays for Diaiomacece, has been productive of good results. 



Geological Purvey Office, n t? i\ -u 



Jekmyn Street, S.W. ^- ^- De EanCE. 



HUNST.ANTON "RED CHALK." 

 Sir, — Allow me to call your attention to the subjoined extracts 

 from the Survey Catalogue of Eock Specimens apropos of the para- 

 graph on Hunstanton Eed Limestone, by W. S. M., at p. 114: of the 



