602 A. J. JTJKES-BROWJSTE ON THE EELATIVE AGES OE 



spread of gravel, sand and ]oam, which forms an open plain between 

 Ormsby Park and Tetford, the glacial age of the whole being proved 

 by an intercalated patch of Boulder-clay near the western end of the 

 deposit and beyond the present sources of the Calceby Beck. 



It appears therefore that the Calceby and Ormsby valleys are 

 choked up with glacial deposits, and that the present beck has not 

 been able to excavate its channel down to the bed of the ancient 

 river by which the valley was originally formed. 



If we now turn to the Steeping valley we find that the Boulder- 

 clays sweep round the southern end of the Chalk Wolds into the 

 bay-like entrance of this valley, and extend in a narrow tongue far 

 up the tributary valley of the Skendleby Beck, which comes in from 

 the northward. Beyond the village of Partney, however, about a 

 mile above the point where the Skendleby Beck enters the main 

 valle}^ not a trace of glacial clay or gravel is to be found ; the 

 Boulder- clay terminates abruptly at this point, and not the smallest 

 remnant exists further up the main valley or in any of its other 

 tributaries to indicate that it ever had any further extension. This 

 limit is only about two miles distant from a line drawn across the 

 mouth of the valley from Halton to Candlesby. 



The ancient outlet of the Skendleby Beck is buried beneath the 

 glacial deposits *, and is doubtless at a much lower level than the 

 present bed of the Steeping river. This stream has excavated a 

 channel through the western edge of the Boulder-clay, and down to 

 the underlying Kimmeridge Clay, being evidently turned aside by 

 the great mass of the Boulder-clay which fills up the bay-like entrance 

 to the valley. 



It is worthy of remark in this connexion that the gravels here 

 intercalated between the upper and lower sheets of Boulder-clay 

 have yielded an abundance of mammalian remains. 



From the termination of the Boulder-clay near Partney to the 

 furthest point at which the Kimmeridge Clay is exposed, viz. near 

 Salmonby, is a distance of seven miles ; it would appear therefore 

 that the Lower Neocomian sandstone has been stripped off the 

 Kimmeridge Clay throughout the whole of this distance during the 

 time which has elapsed since the foimation of these Boulder-clays ; 

 that is to say, the greater part of the Steeping valley is entirely 

 of Postglacial origin. On the other hand the whole of the Calceby 

 vallev was formed before the accumulation of the Purple and Hessle 

 Clays t. 



Mode in ivhicli the Steeping Valley was formed. — I have already 

 mentioned that the valley of the Tetford Beck is really continuous 

 with that of the Ormsby Beck, the intermediate portion being a 



* See Q,u*irt. Journ. Geol. Soc. vol. xxxv. p. 403. 



t Mr. S. V. Wood makes a great distinction between these clays, and even 

 excludes the so-called Hessle Clay from the Glacial series altogether. I have 

 not been able to detect any sign of unconformity between them, but on the con- 

 trary believe that they are parts of one continuous series, though I am still in 

 doubt as to the exact relations of this red and purple series to the Chalky 

 Boulder-clay. 



