— 
BOULDER-CLAY IN LINCOLNSHIRE. 411 
origin, but is as much a moraine profonde as the purple boulder-clay 
or even as the great chalky till itself. This,” he says, “is proved 
not only by the character of the clay, but also by the mode of its 
occurrence” *. It does not appear, however, that Dr. Geikie made 
himself acquainted with its mode of occurrence beyond the limits of 
the localities which he mentions; he does not attempt to account 
for the restriction of the deposit to the eastern side of the Wolds, or 
for its position in the valley of the Steeping. It is unfortunate 
that Dr. Geikie did not enter more fully into the special behaviour 
of the Hessle Clay, as itis precisely this which, to my mind, furnishes 
the strongest arguments in favour of its formation by coast-ice ; 
and the facts stated in the preceding pages appear to constitute 
difficulties in the application of his land-ice theory. 
As regards the characters presented by the Hessle Clay at Kelsea, 
Dr. Geikie describes them in some detail. He observes that where 
it rests directly on the Chalk its basement bed is one of angular 
chalk débris. But this is only what we should expect in the case of a 
shore deposit ; and according to Mr. 8. Wood the same bed is found 
at the base of the Hessle gravel. Mr. Geikie, indeed, admits that no 
stress can be laid on this fact as being specially favourable to the 
land-ice theory. His next assertion, that there is no trace of 
bedding in the deposit, must be taken, I presume, as meaning that 
none was visible in the sections he had the opportunity of seeing ; 
I can youch for the existence of laminated loams being clearly 
intercalated in the clay at more than one locality (vide pp. 403, 404). 
Again, he describes a section where a tongue of the Boulder-clay 
is intruded among the subjacent sands, and he looks upon this as ° 
evidence for the agency of land-ice; I apprehend, however, that the 
powerful agency of coast-ice is quite adequate to the production of 
a similar result. Exactly similar phenomena are presented by 
the so called Cromer till, which is both overlain and underlain by 
marine deposits, and portions of which are certainly interbedded 
with the laminated series below. The section given by Mr. Geikie 
appears therefore equally explicable by the one theory as by the 
other, and cannot be taken to prove the correctness of his own view. 
Finally, since we know that coast-ice is capable of accounting for 
such phenomena as are presented by the Hessle Clay in Lincolnshire, 
and as no direct evidence for its morainic origin has yet been adduced, 
I am strongly inclined to adopt the former view, as first suggested 
by Messrs. Wood and Rome. 
The following are the principal facts in fayour of this hypo- 
thesis :— 
(1) The occurrence of marine mollusca in the sands and gravels 
which underlie it, proving that the area was a sea-bottom at a time 
immediately preceding the formation of the superjacent clay. 
(2) The distinct indications of the frequent interposition of 
stratifying aqueous agency, viz. the interbedded layers of laminated 
loam and sand, and the occasional lateral passage of the clay itself 
into similar laminated loam. 
* ‘Great Ice Age,’ second edition, p. 374 
