CHAPTER VI 



THE SILURIAN PERIOD. 



NEXT in order, if the series of palaeozoic deposits were complete 

 in the Malvern district, should follow the great group of richly 

 fossiliferous strata explored as Bala rocks in North Wales by 

 Sedgwick, classed as Llandeilo and Caradoc rocks in South Wales 

 and Salop by Murchison. The whole group is absent. There 

 was perhaps a separation of the whole south-eastern part of the 

 sea during the Bala period, so that no sediments of that order 

 fell in the Malvern area: none such can be traced about Usk, 

 Mayhill, Malvern, Abberley, or Woolhope. In these cases gene- 

 rally the horizon of Bala is invisible; but it is not so at Malvern. 

 The group of rocks is not here, and the fossils, speaking freely, 

 are absent also. No example of Asaphus Buchii, no Trinucleus 

 ornatus, no Lingula granulata : the period is not represented by 

 stratified deposits. 



During this period, and specially in the earlier part of it, were 

 great disturbances of the sea-bed on the west; great outpourings 

 of fused rocks, as in the Arenig and other mountains. Nor shall 

 we be rash in assigning to this period a part at least of the igneous 

 rocks ejected among and above the black shales of Malvern. Let 

 us suppose that, in connection with these operations, the Malvern 

 area was raised for a time, and placed above the reach of that sea 

 of the west, which was at this time so prolific in life in depths 

 where now Aran-Fowddy and the Berwyns rise aloft in air. A 

 general depression followed. 



Then came in settled order the series of arenaceous, argillaceous, 

 and calcareous beds, whose physical history is not materially dif- 

 ferent from other deposits of analogous composition in Silurian 

 districts. The whole series indicates a long-continued ^subsidence 



