SILURIAN ROCKS. 



S7 



hich makes a transition in 



rock character to the lower beds of the old red 



lie. These Wenlock and Ludlow rocks 



British strata which include con- 

 ic. The exposure o( 

 dock In: at the surface forms the hill 



south-west from Coalbrookdale, known as 



- indicate shallow-water conditions 



by the May Hill sandstones at their base. The 



which are only hardened muds, were pre- 



oia R«>d SettUf sfoW 



. Ca<rT«-yTu 



M,\r OF av Ini.ii r. 



io. — Map showing a don* | Silurian rocka 



nudation of the old re irbonif- 



led continuously over the whole 



limestones, formed 



nd the 

 necessarily formed 



The Wenh 

 ber of corals, and 

 in geological time 

 many of the beds 

 crinites, and some 

 the same conditio 



further from shore; while the 

 of i ,d crinoids, 



reach of sediment, but not 

 in deep water. 



mestone includes a large num- 

 is the first indication met with 

 of a British coral reef, though 

 are largely composed of En- 

 of Brachiopod shells, showing 

 ns as are afterwards repeated 



