478 Correspondence — Mr. T. Mellard Reade. 



he admits that small pockets of such clay were also seen above it. 

 Why does Sir Henry Howorth only quote the latter statement and 

 not the former? 



If Sir Henry will study the facts in the field, and especially if he 

 will have a few excavations made at any of the localities where the 

 relative age of the beds is doubtful, he will earn the gratitude of 

 geologists, but his present methods of controversy do not entitle him 

 to their respect. 



There is an excellent field for research at Brandon ; it is easy to 

 prove that some of the brick-earths pass under the Boulder-clay, 

 but there still remain two points to be decided, (1) do such brick- 

 earths contain flint implements ? (2) are there not other deposits 

 containing flint implements and mammalian remains which rest on 

 this Boulder-clay ? 



Let Sir Henry Howorth do for Geology what General Pitt-Rivers 

 has done for Archeeology, and we will welcome the results. Mean- 

 time any further endeavour to support a preconceived theory by a 

 partial examination of written statements will hardly be welcome to 

 readers of this Magazine. 



September 6th, 1892. A. J. Jukes-BroWNE. 



SHAPES OF SAND GRAINS. 



Sir, — It is pleasant to hear from so experienced an observer as 

 Mr. Cecil Carus-Wilson that the views expressed in my paper on 

 Glacial Geology on the generally superior roundness of Marine 

 Sands as compared with river sands are borne out by his own in- 

 dependent observations. 



My remarks on the rounding of sand grains were strictly limited 

 to its bearing on glacial geology. The sand-dunes referred to were 

 those of our own coast. Here from Crosby to Southport we have 

 23 square miles of Blown sand which I have been living on and 

 working in as an engineer for the last 25 yeai's. I can find no 

 detectable difference in form between the sand grains of the shore 

 and those of the dunes. 



Desert sands are of course out of the question in glacial geology, 

 and I quite agree with Mr. Carus-Wilson's observations relative to 

 them. His other interesting observations shall have my attention 

 in future work. 



I have found my sand investigations of the greatest use in glacial 

 geology, though not originally undertaken for that purpose. The 

 polish in some of the glacio-marine sand grains is quite remarkable. 

 No glacial shelly sands that I have examined fail to show much 

 rounding of the grains — not only those quartz but the undoubted 

 glacially derived materials also. There are also other glacial shelless 

 sands of which there are the most convincing evidences of marine 

 origin that exhibit equal evidences of extreme attrition. 



The non-marine but purely' glacial sands are invariably angular. 

 I have just received from Professor J. J. Stevenson, of New York, 

 a sample of sand from Glacier Bay in front of the Muir Glacier, 

 Alaska, which is remarkably angular in grain. 



