124 GEOLOGY or THE BEISTOL COALFIELD. 



amygdaloidal character maybe easily seen. Their appearance and 

 chemical composition are yery similar to the Trap seen near the 

 Charfield Station, both in the quarry near the roadside and on the 

 banks of the Midland Eailway. 



In this quarry may be seen some pieces containing numerous 

 small specks of Lime, and probably formed from Limestone 

 calcined at the time of eruption. The following analyses of the 

 original Llandovery Sandstone and the Charfield section appear 

 to prove that the latter is not all true Greenstone, but formed 

 from strata altered by close contact with highly heated lava. No. 

 1 is analysis of the original Llandovery Sandstone, while Nos. 2 

 and 3 are of two distinct places in the same Charfield quarry. 



100-00 ... 10-000 . . 100^00 



In the Llandovery Sandstone are scales of Mica, which are also 

 to be detected in the Charfield quarry and on the sides of the 

 Damory Greenstone. 



Augite could not be found, as probably may have been expected, 

 for that substance is not very generally perceived with the Quartz 

 rocks. Perhaps this idea of altered Sandstone gave rise to Sir 

 E. Murchison'sname of " Volcanic Grit," which is an appropriate 

 one. 



Mr. Aikin alludes to these beds as Micaceous Sandstone dipping 

 away from the Trap at a high angle. (Geol. Trans. Vol. 1, old 

 series, 212.) 



The igneous rocks of Eroadfield Down, Uphill, and '^"eston- 

 super-Mare are of much later age, and have a totally distinct 

 appearance and composition. They are basaltic in their 



