MIDLAND UNION PRESIDENT'S ADDRESS. 173 



satisfactory to see cleared up. A few fish scales have been fouud at 

 Newark, annelid tracks occur now and then ; a Cheirotherium footprint 

 was found some years ago by Mr. Irving at Colwick, and lately Mr. 

 Wilson caine upon quite a shoal of lislies in a seam of marl at the 

 very base of the Waterstoues in Colwick Wood. Above the Triassic 

 rocks come the Rhsetic beds, a thin series of dai'k-coloured shales 

 which help to connect the Trias with the Lias. The outcrop of these 

 beds strikes north and south and N.E. and S.W. across the county, 

 from Gainsborough to Newark, and thence by Elton and Stauton-ou-the 

 Wold into Leicestershire — and is often indicated by a low level-topped 

 escarpment. Exposures of the Ehaetics are rare, but they may be seen 

 in the gypsum pits at Newark-on-Trent, and there is a very good 

 exposure at Gainsborough. 



Last of all comes the Lias. The lower Lias limestones and shales 

 only are represented in Notts. They crown the high ground in the 

 south of the county which runs from Bunny to Cropwell Wolds, and 

 stretch thence to the Vale of Belvoir. The blue lias limestone is 

 worked for cement at Baruston. A detailed account of the Lias would 

 belong rather to the geology of Leicestershire than of Notts. The 

 excursion to-morrow to Belvoir Castle under the able leadership of 

 Professor Blake, will give the members of this Association an oppor- 

 tunity of examining these rocks in that county. 



Glacial drift occurs in several places, usually as thin patches of 

 sand and gravel, but does not as a rule attain a sufficient thickness to 

 seriously modify the nature of the soil. The high ground extending 

 from Robin Hood's Hills through Anuesley Park is thickly covered 

 with drift. Near Blidworth are large isolated masses of cemented 

 drift gravel. On the high ground, six miles south of Nottingham, 

 where the Lias comes in, there is a great accumulation of Boulder Clay, 

 which at Stanton-on-the- Wolds attains a thickness of sixty feet or 

 more, and is largely constructed from the grinding down of the Lias, 

 Rhsetic, and Keuper shales of the district, but contains erratics which 

 have come from considerable distances. 



The floor of the valley of the Trent, which has in this district an 

 average width of about two miles, is occupied by alluvial deposits of 

 gravel and sand, about twenty feet in thickness on the average, with a 

 top crust of alluvial silt or mud or a peaty soil a foot or two in thick- 

 ness. The Leen valley is occupied by a narrow fringe of similar 

 deposits, as also are some of the smaller brooks and a rather extensive 

 alluvial flat formed of stiff dai"k clay, known as Bingham Moors, lies 

 on the south-east side of the district. 



MOLLUSCA. 



In MoUusca the district is fairly well represented. We have 

 recorded 100 speciea in the county of Notts out of about LSO British 

 species. 



