of Tilgate Forest in Sussex, S6S 



deposits in tJiose localities that are most accessible to the geolo- 

 gist, is certain ; but their emergence from beneath the weald 

 clay, the superincumbent formation, is so obvious, as to leave 

 not the shadow of a doubt that they were originally entirely 

 covered by the clay, and that their present approach to the sur- 

 face is owing to the operation of that uplifting power, whose ef- 

 fects are strikingly manifest throughout the whole of the south- 

 eastern part of England. The annexed section of the strata 

 from Brighton (on the coast of Sussex) to Tilgate Forest, is made, 

 not from theory, but from actual observation, and will, I trust, 

 satisfy the writer of the " Observations,'' of the correctness of 

 my remarks. 



JSrf^^ion, South Downs ' -^ y-^^Svsc. 



Ua stivrf JSandFormaTco 7^ 



If the section wer^tcontinuedxjn to London, the several for- 

 mations would re-app'eary but in an ascending series (vide Phil- 

 lips and Conybeare's Sec^tions), The attention of geologists was 

 first directed to the remarkable nature of the fossils of the strata 

 of Tilgate Forest, by my work on the Geology of Sussex, in 

 1822 ; and although, at that period, the geological position of 

 those deposits was not determined, yet I had not the slightest 

 doubt that they were situated beneath the weald clay. The only 

 question was, whether they should be ranked with the purbeck, 

 or the iron sand ; their emergence from beneath the more recent 

 formations was too manifest to be questioned (vide Illustrations 

 of the Geology of Sussex, p. 57). Subsequent observations con- 

 vinced me, that the strata of Tilgate Forest, instead of being li- 

 mited, as I had at first supposed, to a small district, were co-ex- 

 tensive with the iron-sand, and might be traced through Sussex 

 to the coast at Hastings ; and a paper, describing the result of 

 my researches, was read before the Geological Society of Lon- 

 don, in the same year (1822). 



The writer of the observations states, " that there are nume-^ 

 rous considerations that might lead us to consider the two depo^^ 

 sits (viz. the Stonesfield slate and Tilgate limestone) as having 

 been formed at a period which would be much newer than that 



