Mr Trimmer himself says, " That maps of the surface geology 

 of these Islands would be of great utility, must be obvious to 

 everyone who combines agricultural with geological knowledge, 

 and who is aware of the extent to which our country is covered 

 by the superficial deposits, whether we call them Drifts, Erratic 

 Tertiaries, or by any other name." In consequence of the hint 

 given by Prof. Johnston, Mr Trimmer was induced to enter 

 upon the task of mapping the surface geology of Norfolk during 

 the years 1844 — 1846. The results of this survey were entered 

 on the ordnance-map, and the author contributed a paper on 

 the Distribution of Soils to the Journ. Roy. Agric. Soc. Vol. vii. ; 

 while the more purely geological details were embodied in a 

 memoir written for the Geological Survey but never published, 

 the main generalizations were however given in two papers 

 communicated to the Geological Society in 1851 \ He regards 

 the distribution of the Drifts or Erratic Tertiaries of Norfolk to 

 be such as would have resulted from the action of shore-ice on 

 gradually sinking land, and classifies them under two heads : 

 (1) Boulder Clay, or Loiuer Erratics ; (2) Sands and Gravels, or 

 Upper Erratics ; believing this arrangement to hold good over 

 the whole of the Eastern Counties. (See Tabular View in 

 q. J. G. S. Vol. IX. p. 295. 1853.) 



In 1857 (just before his decease) Mr Trimmer became 

 aware of the existence in the Gorleston cliffs of an Upper and 

 Lower Boulder Clay separated by a thick mass of sand. In his 

 former papers he had thought that there was only one Boulder 

 Clay, for having traced the Upper Clay (characterised by an 

 abundance of Oolitic detritus) over the south of Norfolk, and 

 believing the Cromer Till (containing blocks of Scandinavian 

 origin) to be confined to the north of the county, he had sup- 

 posed the two clays met on the same level. The sands under- 

 lying both he referred to the Crag series, but he finally accepted 

 the results of Mr Gunn's observations as establishing the fact 

 that the Upper Boulder Clay overlaps the Lower "with a mass 

 of sand interposed'." In 1864 Mr S. V. Wood junr. read a 

 paper before the Geological Society "On the Drift of the East 

 of England and its Divisions." He demonstrated' more fully the 



1 Quart. Journ. Gcol. Sue. Vol. vii. p. 19 and 38. « Ibid. Vol. xiv. p- 171. 



