212 A Sketch of the Natural History of 



The marl beds form the most peculiar feature in the al- 

 luvial strata of the Cheshire plain. These occur in great 

 abundance in every part of the district ; being found not 

 only under the common soil, but occasionally, as on the 

 borders of Delamere Forest, interposed between layers of 

 sandstone rock. The Cheshire maris are also very fre- 

 quently met with in large detached masses, twenty or thirty 

 feet in thickness, in the working out of which, it is not 

 unusual to find large assemblages of fragments of the older 

 rocks. Portions of granite, often of large size, and show- 

 ing on their surface evident marks of attrition, are among 

 the most common appearances in these collections : no 

 granitic rocks are found within fifty or sixty miles of this 

 district. 



The divisions which I have pointed out in the Cheshire 

 plain are still further marked by the course of the streams 

 in this tract of country. The Dee is the great river of th« 

 western plain ; the Weaver and its subordinate streams re- 

 ceive all the waters of the southern division ; while the 

 Mersey and its tributaries do the same in the northern por- 

 tion. From their local relation to the great beds of rock- 

 salt, the streams of the southern or central plain possess a 

 peculiar importance. 



The Weaver rises in the Peckforton Hills, near the 

 Shropshire border, runs for some miles towards the south- 

 east, then n)aking a sudden flexion to the north, continues 

 in this direction, by Nantwich and Winsford, to North- 

 wich, about thirty miles further. Here it takes a north- 

 westerly course to Frodsham, where it expands into a sandy 

 aestuary, connected with the channel of the Mersey. It 

 receives its principal accessions at Northwich, where it is 

 joined by the united streams of the Dane and Weelock 

 from the south-east, and by a stream called Witton Brook 

 from the east. At Anderton, a little below Northwich, the 

 valley,which has hitherto been comparatively wide and flat, 

 is suddenly contracted by the approach of two ranges of 

 high ground; that on the western side of the river con- 

 necting itself by a gradual rise with the heights of Delamere 

 Forest; the opposite one passing by a series of irregular 

 elevations into the range of high land, which separates the 

 southern from the northern plain. At Frodsham the river 

 flows, as I before mentioned, between the termination of 

 this high ground and that of the ridge which crosses the 

 county°from north to south, the hills thus opposed cor- 

 responding perfectly in appearance and structure. We 



haye 



