472 S. V. WOOD, JUN., 7EK 



large masses of gravel have been laduoed into the brickearth, 

 giving rise to contortions in a sim: i way to the masses of marl. 

 So far as these masses are found m Korth Norfolk, so far only, 

 whether in the cliff section or inland, do tho great contortions 

 extend; for beyond this area contortions are nre and of trilling 

 extent, and are due to other causes. The introduci ion of these masses 

 and the formation of the contortions (which, as Ivsfore observed, are 

 not confined to the upper part of the Lower GlaciJ formation called 

 par excellence the " Contorted Drift," durmg the accumulation of 

 which they originated, but often extend ^^"wn bo the Lower or Blue 

 Till part, the sand (hi) at the base of it being in some cases even 

 squeezed out) have evidently been the result of grounding bergs. 

 These were of the kind called by Nordenskiold false bergs, which he 

 describes as large fragments that fall from the perpendicular face of 

 lofty ice which enters the sea on a shore of easy slope and in water 

 of moderate depth, as distinguished from true bergs, which are far 

 larger fragments of a glacier which enters the sea through a nar- 

 row, deep, and steep- bottomed fiord, and from which they are lifted 

 and floated off by the buoyancy of the water*. The ice at the 

 time of maximum submergence resting thus on the chalk Wold, 

 and terminating in the sea there in the former manner, the moraine 

 which it formed being chalk, with the slight intermixtures just 

 described, was extruded into water of no great depth, while deposits 

 of a finely laminated character were thrown down from the copious 

 supplies of chalk silt borne out by the freshwater streams that issue 

 from beneath the sea-faces of glaciers. The same silt, carried 

 further, was in that part of Norfolk which extends past Cromer to 

 Weybourne extensively interstreaked and intermingled with the 

 brown mud forming the brickearth of the Contorted Drift, its quan- 

 tity increasing palpably in the direction of the Lincolnshire Wold. 

 A mass of ice breaking off from the vertical face of this glacier 

 being of so nearly the same specific gravity as water, and most of it 

 falling from a height, would enter the water with force sufficient to 

 carry it to the bottom, which was not deep, and also to force 

 its jagged surface into that bottom, whence rising it would lift 

 portions proportional to the size of the berg and to the force with 

 which it fell. Drifting towards East Norfolk, where the submer- 

 gence was least, these bergs passed to shallow water, so that they 

 grounded, churning up the soft bottom there ; and as they melted 

 they left whatever they carried, which in most cases was part of the 

 bottom, which they scooped up as they fell from the glacier. Some- 

 times, however, where the bottom was gravel, they have, in floating 

 off again, carried away portions of this, and grounding in Norfolk 

 have forced this into the deep and soft bottom formed of 6^ and hS^ 

 and even removed and reintroduced portions of these beds them- 

 selves, so as to cause perplexing interruptions to the continuity of 

 the stratiflcation in the coast-section. The disappearance of these 

 masses and contortions as these beds thin off east of Mundesley, in 

 the coast-section of Sheet 68, especially when regarded in connexion 

 * Geol. Mag. vol. ix. p. 363. 



