KECENTLY-EXrOSED SECTIONS IN GLACIAL DErOSITS AT IIENDON. 57'> 



33. On aome IIecently-Exposed Sections in the Glacial Deposits 

 at Hendon. By Henry Hicks, M.D., F.R.B., 8ec. Gcol. Soc. 

 (Read May 27, 1891.) 



[Plate XXII.] 



Contents. 



Page 



I, ]ntro(luctiou r)75 



II. Some Kecently-exposcd Sections 'ub 



III. Distribution of the Glacial Deposits 581 



LV. Conclusions 582 



I. Introduction. 



For the past twenty 5''ears I have watched with interest the 

 numerous exposures which have been made in the Glacial deposits 

 at Hendon and in the adjoining areas, in making foundations for 

 buildings, in digging for gravel, and in excavations in the course 

 of laying down sewers. Some of the observations which I have 

 made have been incorporated in the writings of authors who have 

 referred to this area*, but hitherto I have avoided publishing the 

 general results owing to the fact that new exposures which added 

 fresh information were constantly being made. The recent com- 

 pletion of the main sewering of most of the parish of Hendon, 

 however, has furnished data for giving a fairly complete summary 

 which I now place before the Society. Twenty years ago the 

 nature, extent, and boundary of these deposits were very imper- 

 fectly known, and doubt existed as to how they should be classified. 

 When Mr. Henry Walker was making his researches in the Glacial 

 deposits at Finchley, the results of which he communicated to the 

 Geologists' Association in 1871, I expressed to him the opinion, 

 which he mentions in his paper, that the sands and gravels at and 

 near Hendon ought to be classed with the so-caUed Middle Sands and 

 Gravels of the Eastern Counties. This view, which I still hold, is 

 now generally adopted ; but the clay-with-flints which overlies 

 these beds on the Hendon Plateau has only recently been satisfac- 

 torily demonstrated to be, in part, the equivalent of the Chalky 

 Eoulder-clay at Finchley, Whetstone, &c. 



II. Some Recently-Exposed Sections. 



When the sewer was being carried through Parson Street, 

 directly opposite the Yicarage, 2G8 feet above Ordnance datum, a 

 considerable thickness of Poulder-clay, resting on sand and gravel, 

 -was exposed in the excavation. It was of a bluish-grey colour, 



* H. Walker, Proc. Geologists' Assoc. (1871) \ol. ii. p. 288; Bell, Quarterly 

 Journ. Sci. (1878) ; Whitaker, ' Geology of Loudon ' (1889). 



