GEOLOGY OP THE BRISTOL COAL-FIELD. 317 



with the characteristic beds of fossils can be stadied with so much 

 facility and advantage, that we do not hesitate to take the Clifton 

 section as a typical example, following as a guide the accompanying 

 sketch. 



The Section commences with Devonian strata 360 feet thick, 

 passing gradually through 500 feet of Lower Limestone shales, 

 then through 2000 feet of Mountain Limestone, and finishing off 

 with 400 feet of Tipper^ Limestone shales and grits, and 1000 feet of 

 Millstone grit. 



Every bed may be studied without any dangerous climbing, and 

 with the greatest facility, and in order to facilitate the labours of 

 those who may wish to pay a visit, and who may not be conversant 

 with the locality, the following description, it is hoped, will be 

 amply sufficient to supply the place of a guide. The number of 

 feet indicate the vertical distance from the commencement of the 

 section below Cook's Folly, taking the railway as the datum line, 

 while the numbers of the several beds correspond with those on the 

 diagram. As may easily be imagined, the catalogue of fossiliferous 

 beds is so immensely long that only a few of the most interesting 

 have been taken. 



The Devonian beds that commence the first 360 feet of the 

 section, are generally sandstone, containing Mica, but devoid of 

 Carbonate of Lime and Fossils. At the distance of 327 feet are 

 three remarkable beds of quartzose conglomerate 6 feet thick, 

 divided by thin partings of purple and green marls. The pebbles 

 are pieces of quartz which have had their angles completely worn 

 away from long continued water action, and are probably the bed 

 of an ancient river near the sea. 



Thirty-three feet above the conglomerates is the first bed that 

 contain any appreciable quantity of lime, and may therefore be 

 considered as the commencement of the true Carboniferous section. 

 The junction of the Old Bed and Carboniferous is so gradual that it 

 is impossible to say where one ends and the other begins, but the 

 junction beds may be included between the conglomerates and the 

 bed now mentioned. 



