INTRODUCTION. xix 



present with the contortions ; and as these masses cease eastwards, so do the contortions, 

 the drift becoming, save for the presence of sandgalls, uncontorted ; and about Bacton and 

 Hasboro' putting on the stratified condition shown in Sections I and II, wherein bands 

 of fine mud and sand alternate with chalky silt, and bands of clay more or less intermixed 

 with chalk debris. Some of this interstratified material is scarcely distinguishable from 

 the material of the great chalky clay No. 9 ; while more of it is identical with the marl 

 of which the masses, No. VII, are composed. These masses, again, are identical with a 

 formation that covers much of North-west Norfolk, and occurs also in the South-west, 

 consisting of soft chalk finely ground up by the enveloping land ice sheet of the period, 

 and spread out from its seaward termination into a deposit that frequently shows stratifica- 

 tion (sometimes very fine), and in which great sandgalls, like those so abundant in the 

 red mud portion of it, occur. 1 It is in the district where this reconstructed soft chalk of 

 North-west Norfolk changes horizontally into the red mud or brick-earth that the included 

 masses of marl, such as the Coast section presents, become frequent ; being sometimes 

 acres in extent, and worked for Marl pits, or for limekilns. The mass supplying one of 

 these limekilns shows itself enveloped in the red mud in the Cliff section on the south side 

 of Cromer Town, and another, west of Woman Hythe, which is some 300 yards long, has 

 sunk down to the chalk, squeezing out the Till on either side. This reddish-brown mud 

 is easily followed from the Cromer coast southward to Norwich in a continuous deposit ; 

 but the Marl masses in it cease a few miles north and north-west of that city. About 

 Norwich it is worked as brick-earth in numerous sections, but, as the contortions and Marl 

 masses are absent from it here, 2 it has been regarded by the Norfolk Geologists as " the 

 Lower Boulder clay." There can be no question that in these contortions and Marl 

 masses we have evidence of the grounding in the red mud of icebergs detached from the 

 sea foot of the land glacier occupying the Chalk country, which were laden at their bottoms 

 with masses of the same degraded chalk which was extruded from the glacier foot, and 

 spread out under the sea over North-west Norfolk. South of Norwich the deposit becomes 

 very intermittent, and often very thin, its thinness being apparently due principally to 

 intra-glacial denudation. 



1 Even in this district it will suddenly change into a sandy stratified silt, or into compact yellow 

 brick earth. Sections of either of these conditions of this drift occur with the clay No. 9 over it (beyond 

 the limits of the map) near Guist, in the Wensum valley ; that valley having been excavated out of the 

 contorted drift, in the interval between this drift and the Middle Glacial No. 8, which, with the clay No. 9, 

 occurs in the valley, and in some places in the bottom of it. 



2 It is contorted in a pit four furlongs north-north-west of Thorpe Asylum, but that, we think, is not a 

 contortion of the period of this drift, but due to the intraglacial excavation of the valley here, which causes the 

 later Glacial beds to plunge into the valley. The pit three furlongs north-west of Upton Church (near the 

 eastern end of section 0), shows in the most striking manner the contorted drift in its red mud form, 

 contorted, and containing sandgalls, just as it is about Cromer, overlain by the great chalky clay No. 9. 

 Section II represents a spot in Hasboro' Cliff, where a tongue-like piece of the contorted drift (finely 

 stratified with chalky silt and clay with chalk de'bris) has been lifted during the accumulation of the 

 overlying sand, 8, which has fouud its way under the piece without its becoming detached. 



