80 MR. B. THOMPSON ON THE GEOLOGY OF THE [Feb. 1 899, 



The large nodules are found in diminishing numbers at about the 

 junction of the blue clay with the brown Boulder Clay, rising with 

 the latter, to about 53 miles 56 chains : that is, to the point where 

 the Boulder Clay ceases entirely. 



In connexion with this I may again refer to a description of 

 some Drift-beds near Woodford, south of the 67th mile.^ I decided 

 to examine these again, in the light of the conditions more critically 

 investigated near Rugby. Between R and 8 {op. cit. pi. xiv), the 

 Great Central Railway branches, one part continuing the main 

 line, and the other forming a connexion with the East &: West 

 Junction Railway. In the branch-cutting nearly the whole section 

 appears to be undisturbed Upper lias : east of this, on the main 

 line, however, and only a short distance away, where a bridge 

 crosses it, the following section is seen : — 



Feet. 



1. Soil, with a little gravel 1 



2. Mixture of sand and clay ; very red, looking at a distance I , . -.^ 



as though almost a sandstone ; blue clay observed, which [ ^ 

 on a closer inspection is seen to contain a varietv of stones J 



3. Blue clay with numerous Upper Lias fossils, Leda ovum '\ 



being especially abundant. A close inspection shows that I , r 



it also contains pieces of red sandstone (Northampton [ 

 Sand ?), chalk, pebbles, etc j 



4. Upper Lias Clay, real undisturbed blue clay showing an "I '^ ^ a 



irregular junction with 'No. 3 J 



Where ISTo. 3 joins on to JN'o. 4 it can be noticed that the former 

 is distinctly of a browner tinge. It appears to me that No. 2 

 represents the brown Boulder Clay, and No. 3 the blue local 

 Boulder Clay of Rugby. 



(ii) Brown and grey contorted Boulder Clay. 

 (Lower Boulder Clay.) 



In some places resting on the Lower Lias, in some on the blue 

 Boulder Clay, and elsewhere on an intermediate sandy or chalky 

 layer, and always below the gravel-beds, there was found near 

 Rugby a brown or grey Boulder Clay or Loam. The colour varied 

 much, according to whether it was wet or dry, as also did its physical 

 characters. When wet it mostly looked like and cut like a stiff 

 clay, in mass; but really it was most irregular in composition, 

 ranging from a tolerably pure clay through loam to nearly pure 

 sand. Yery considerable portions of the mass consisted of an 

 irregular mixture of sand and clay, the sandy layers being sandwiched 

 in with the clay, and these parts, without exception, seemed to be 

 highly contorted, the contortions being beautifully shown when the 

 material was half dry, owing to the different hygroscopic capacities 

 of the sand and clay. A better idea of this deposit will be gained, 

 probably, from the following reproduction of my notes made on 

 various occasions in 1897. 



1 See Proc. Geol. Aisoc. vol. xiv (1896) p. 427. 



