250 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 9, 



ford, whose skill in the use of surveying instruments was of great 

 service. Where the strata were exposed in a vertical escarpment and 

 were accessible, they were accurately measured, but in other cases 

 their thickness could only be ascertained by means of the sextant. 

 By putting together the varied observations thus obtained, we con- 

 structed the section given at p. 242, supra. It is drawn on a uni- 

 form scale of height and distance, so that it exhibits the precise profile 

 of Leckhampton Hill, without those exaggerations seen in others where 

 two scales are adopted. The height of this hill above the sea has been 

 ascertained by the Officers of the Ordnance Survey to be 978 feet 

 (see Annals and Magazine of Natural History, Second Series, vol. v. 

 p. 257). I will now proceed to enumerate the strata here observed, 

 adopting, as far as they go, the nam.es employed in Sir R. Murchison's 

 ' Geology of Cheltenham.' 



(1 .) Trigonia grit : so called from the abundance of Trigoniae 

 which it contains. It is better exhibited in other localities, especially 

 at Cold Comfort Farm, but it may be seen in the quarries on the high- 

 est part of Leckhampton Hill, its thickness being about 7 feet. 



(2.) Gryphite grit : characterized by the very peculiar and con- 

 spicuous shell " GryphcEa cymbium.^'' Extensively quarried on the 

 summit of the hill, and used for roads, building walls, &c. Thick- 

 ness 7 feet. 



(3.) Beds of brown rubbly oolite, not employed for any purpose, 

 but exposed between the inclined planes and the Cirencester road. 

 It contains a considerable variety of fossils. Thickness 24 feet. 



(4.) Oolitic freestone, too fragmentary to be of much value for 

 building, and apparently not distinguished by any peculiar fossils. 

 26 feet. 



(5.) Oolite marl, consisting of soft, whitish oolitic stone containing 

 much aluminous matter and some beautifully preserved fossils, and 

 especially characterized by the very peculiar Terebratula fimbria. 

 17 feet. 



(6.) Beneath the marl, the strata for more than 100 feet consist 

 of compact light-coloured oolite. The upper portion forms the best 

 building-stone, and has been extensively quarried ; hence it is more 

 especially distinguished by the name of " freestone." Its thickness 

 at the point where we measured it was 31 feet 6 inches. The lower 

 part of this oolitic mass is coarser and more variable in texture, and 

 is hence more rarely quarried. Numerous and beautiful fossils may 

 be procured in it, but only by great patience and perseverance. The 

 resemblance of these and their matrix, to those of the great oolite on 

 Minchinhampton Common, is very remarkable, and caused consider- 

 able discussion among geologists until the distinctness of the two 

 strata was absolutely demonstrated. This part of the series is 75 feet 

 thick, and is locally known by the name of "roestone." 



(7.) Ferruginous beds, consisting of coarse oolite in the upper part, 

 and of the very peculiar, large-grained oolite or Pisolite (" Pea-grit ") 

 in the lower. A few miles to the south the Pisolite disappears, and 

 is replaced near Painswick and at Haresfield Hill by strata containing 

 ferruginous oolitic grains in a brown paste. This is the precise equi- 

 valent of the well-known oolite of Dundry near Bristol, which may 



