§ IS. MILLSTONE GRIT. 677 



by Dr. Buckland to be the most interesting of any he 

 has visited — but I will describe them in his own eloquent 

 language. " The most elaborate imitations of living 

 foliage on the painted ceilings of Italian palaces, bear 

 no comparison with the beauteous profusion of extinct 

 vegetable forms, with which the galleries of these instruc- 

 tive coal-mines are overhung. The roof is covered as with 

 a canopy of gorgeous tapestry, enriched with festoons of 

 the most graceful foliage, flung in wild irregular profusion 

 over every portion of its surface. The effect is heightened 

 by the contrast of the coal-black colour cf these vegetables 

 with the light ground-work of the rock to which they are 

 attached. The spectator feels transported, as if by en- 

 chantment, into the forests of another world ; he beholds 

 trees of form and character now unknown upon the surface 

 of the earth, presented to his senses almost in the beauty 

 and vigour of their primeval life ; their scaly stems and 

 bending branches, with their delicate apparatus of foliage, 

 are all spread forth before him, little impaired by the lapse 

 of indefinite ages, and bearing faithful records of extinct 

 systems of vegetation, which began and terminated in 

 times of which these relics are the infallible historians. 

 Such are the grand natural herbaria wherein these most 

 ancient remains of the vegetable kingdom are preserved in 

 a state of integrity little short of their living perfection, 

 under conditions of our planet which exist no more."* 



13. Millstone Grit. — The principal coal measures 

 are generally superposed on the group of deposits desig- 

 nated by this term ; but in some districts, these strata are 

 wanting, or appear as a cherty, and sandy rock. The 

 most characteristic bed of this series is the quartzose con- 

 glomerate, termed millstone-grit, which consists of rolled 

 fragments of quartz-rock and granite, of various sizes, 

 from a pear to that of a large pebble, cemented together in 

 * Bridgewater Essay, p. 458. 

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