B ROT) IE — GEOLOGY OV GLOUCESTERSHfRE. 



289 



but useful method we hope to teach some really practical ideas of 

 geological phenomena. 



Impracticable in the present state of kno^Yledge, it would take 

 years to construct such an entire map of the first dry lands, 

 and we have, therefore, selected a portion containing the typical 

 district, and which is certainly correct in its great features, 

 though still wanting in some details ; and in the primitive lands 

 there pourtrayed, the long ridge extending along the western 

 margin of the whole American continent, from the northernmost point 

 of Russian America through the Isthmus of Panama to Cape Horn, 

 the lunulate mass on the north side of the lakes encircling Hudson Eay, 

 with the outlying islands and patches, appear at a glance as the frame- 

 work upon which the existing territory has been elaborated and 

 expanded in the great geological ages which have passed away, and in 

 these remnants the primitive lands are probably very nearly represented, 

 for, as the rock-masses were elevated, it would naturally follow that the 

 more newly-raised and outer or marginal portions would be degraded 

 by the action of the waves, and form the source of the materials of the 

 subsequent deposits during successive geological periods. 



(To be continued.) 



CO^TTRIBUTIONS TO THE GEOLOGY OE GLOUCESTERSHIRE. 



THE LIAS. 



Rv THE Rev. P. B. Reodie, M.A., E.G.S., kc, ke. 



{Continued from pig e 233.) 

 The beds immediately below the Marlstone, which consist of laminated 

 shales and clays often micaceous and sandy, were well exposed at tlie 

 latter place during the formation of the reservoirs, and at Robins wood 

 Hill, near Gloucester, and at Chipping Campden, on the north-eastern 

 extremity of the county, a locality vrhich deserves a special visit. In 

 this part of the series, at the base of the Marlstone, a good deal of 

 ironstone prevails, which, it is said, was in ancient times worked near 

 Gloucester ; it is of some thickness and of excellent quality at Campden. 

 These beds are no where destitute of fossils, among which, at the last- 

 named place, we may especially notice the fine Qpliloderma Gaveyi 

 (one of the brittle-stars,'" some species of which are so frequent in our 



* Some of the recent Opliiuridte have a sh-iguLir habit of shaking off their 

 tender arms when touched, as if in dofiance of their captor, and owing to tliis, it 

 is almost impossible to obtain specimens in perfection. — P. B. R. 



