20 



LOWER LIAS. 



the left bank from Shothonger Common to Brockeridge Common, three miles north 

 of Tewkesbury, whence it takes a straight course to the north-east by Bought on Hill 

 and Pirton to Norton, four miles south-east of Worcester. In describing the structure 

 and contents of the Lower Lias, and its junction with the marls of the New Red Sand- 

 stone along the line just mentioned, we may particularly notice a section at Combe Hill, 

 six miles north of Gloucester, as exhibiting a perfect and conformable transition from the 

 one system into the other. In the descending order we first perceive about 12 thin 

 courses of dark-coloured calcareous flagstones, which are extracted for roads, paving, 

 building, and burning to lime. These courses vary in thickness from 1 to 3 inches, and 

 are separated from each other by stiff marl : the two lowermost bands, known locally as 

 the " Rattler " and the "Bottom bed," are alone burnt for lime. 



The surface of the flagstones is frequently covered with numerous fine and delicate 

 species of Echini ; and bones and vertebra? of Saurian animals have also been found. 

 These beds are underlaid by sandy pyritiferous shale, graduating downwards into cream- 

 coloured marl, succeeded by shivery, finely laminated, black shale, highly charged 

 with iron pyrites and small crystals of selenite, and containing a few thin courses 

 of whitish sandstone. The predominant fossils are 



Ammonites planorhis. M. C. t. 448. 1 

 Modiola Hillana. M. C. t. 212. 



Modiola minima. M. C. t. 210. 



Ostrea. Small unpublished species very abundant. 



Beneath these beds of flagstone, shale, and sandstone, there is a passage, through 

 lightish blue and grey marl, into the green and red marls, which form the upper limits 

 of the New Red Sandstone system ; the beds dipping at an angle of about 1 5° to 

 the south-east. The calcareous bands are known locally under the name of " clay- 

 stones 2 ," and they mark the base of the Lower Lias in its course through Gloucester- 

 shire and Worcestershire. When well exposed, they are always seen to graduate down- 

 wards, through finely laminated black shale, into the same whitish sandstone observed 

 at Combe Hill. Such relations appear in the promontory of Bushley, on the left bank 

 of the Severn, at Corsewood Hill, two miles west of the Haw Bridge ; on the sides of 

 the high road from Tewkesbury to Ledbury ; and at Forthampton Court ; the small 

 Ostrea, and Ammonites Planorhis, being the prevailing fossils. 



An outlier called Longdon Heath, near Upton, has been during many years quarried for limestone, 



1 Remains of Saurian animals have occasionally been found in the Vale of Gloucester, both in those beds 

 and in the Clays above, but as none of these specimens have fallen under my own observation, I cannot state 

 to what species they belong. 



2 This " Claystone " of the Lias was formerly employed as the only road-stone ; but the facilities afforded by 

 water-carriage and the tram-roads, are now so great, that nearly all the high roads of the Vale are repaired 

 with limestone brought from Bristol, which is termed by geologists mountain or carboniferous limestone. 

 Being much more free from earthy matter, and more crystalline than the claystone, it forms a more durable 

 road. 



c 



