48 DE. W. D. LAXG 02T THE STRATIGRAPHY [vol. lxxix, 



more or less irnpersistent, interbedcled seams of fibrous calcite, 

 called ' Beef ' 1 by the Officers of the Geological Survey. 



Descending to the beach at Charmouth, and there forming reefs 

 on the foreshore, the Shales-with-Beef are the most accessible Lias 

 of that place. Yet they are, perhaps, the least known of all the 

 beds. This is doubtless because of the generally unsatisfactory 

 condition of the fossils found in them, and their consequent worth - 

 lessness on the one hand to the native, who finds no sale for such 

 fragmentary and friable remains as the fossils present ; while, on 

 the other hand, the geologist seldom finds specimens more than 

 approximately identifiable, and generally obtains completely satis- 

 factory examples from but three or four horizons. 



Sir Henry De la Beche described the Lias of this coast nearly a 

 century ago 2 ; and, although he generally under-estimated their 

 thickness, the subdivisions that he then made can be approximately 

 correlated as follows, at any rate those five which lie above the 

 Blue Lias limestones : — - 



(5) Irregular bed of Limestone, with nodular concretions, frequently con- 

 taining ammonites ; 2 ieet = Stellaris beds (87-89). 



(4) Slaty marls, with several thin beds of indurated marl ; 67 feet = Black 

 Marl series above J3irc7ii-Tabular and below Stellaris beds (77-88). 



(3) Slaty marls containing small crystals of selenite ; 32 feet= Shales- 

 with-Beef (54-76). 



(2) Indurated marl, containing small, plicated Terebratulee ; 4 feet=Table 

 Ledge (53). 



(1) Slaty marls ; 18 feet = Saurian shales, Fish-Bed, and Fish-Bed shales 

 (50-52). 



In 1860, when Thomas Wright described the Lower Lias of 

 this coast, he but briefly referred to the Shales-with-Beef as 



' thick beds of dark marls, which rest on the Table-bed, formed by Broad 

 Ledge. The lower part of these marls contain numerous compressed Am- 

 monites [JEgoceras Birrfiii (Sowerby)] and layers of nodules forming cement- 

 stones.' (Q. J. G. S. vol. xvi, p. 405 ; and Monogr. Pal. Soc. 1879, p. 49.) 



This lower division of Wright exactly corresponds with the top- 

 most 18 feet of the Shales-with-Beef. Thus the 50 feet of strata 

 lying between Table Ledge and the beds with Microderoceras are 

 left undescribed. 



In his later account (1878-79, 'Monogr. Lias Ammonites' Pal. 

 Soc. pp. 48-51) Wright again omits the greater part of the 

 Shales-with-Beef; for his 'Thick Limestone, "Broad Ledge"' at 

 the top of his ' A. tumeri'' Zone (p. 48) is Table Ledge (53) ; 

 while his ' Nut rocks ' at the bottom of his A. obtusus Zone 

 (p. 50) is the Birchi-TSodcatex (75 a). 



1 H. B. Woodward, ' The Jurassic Bocks of Britain, vol. iii : the Lias of 

 England & Wales ' Mem. Geol. Surv. 1893, p. 65. Applied by the workmen 

 in the Purbeck district (and, probably, elsewhere) to seams of fibrous calcite 

 in the Purbeck Beds ; see W. Buckland & H. T. De la Beche, Trans. Geol. Soc. 

 ser. 2, vol. iv, pt. 1 (1835) p. 11 [I am indebted for this reference to Dr.F. L. 

 Kitchin]. 



2 Trans. Geol. Soc. ser. 2, vol. ii, pt. 1 (1826) p. 21 ; and 'Report on the 

 Geology of Cornwall, Devon, & West Somerset ' 1839, p. 222. 



