45 



OX THE GEOLOGICAL FEATURES OF THE 

 LANDSCAPE. 



EY THOMASJ WRIGHT Esq., M.D., F.R.S.E., F.G.S. 



Dr. "Wright said that at the request of his friend Dr. Bull he had con- 

 sented to give a few remarks on the geological features of the panorama in 

 the midst of which they now stood, but in order that his demonstration might 

 be understood by those who were unacquainted with the subject it would be 

 necessary to state some of the elementary truths of geology. First then the 

 earth's crust consists of two great 'classes of rocks, crystalline or igneous, and 

 aqueous or sedimentary, which are both represented in the landscape around 

 us, for far out in the north you see the Malvern hills and the region of the 

 Woolhope district. The axis or central mass of the Malverns is Syenite, a 

 granitoid crystalline rock of great beauty and variety, and wbich owes its present 

 condition to heat. The eruption of this Syenite caused the upheaval of the 

 chain of hills of which it now forms the'axis. 



The sedimentary rocks you have seen to-day as you rowed down the river, 

 and the conglomerate beds of the old Red Sandstone you examined below, have 

 given you a capital lesson of what is meant when we speak of rocks formed of 

 sediments ; you can have no better example of a mechanical rock than this, 

 for you see the rounded quartz pebbles which had been rolled about on some 

 ancient beach arranged by aqueous agency and subsequently deposited as you 

 have seen them to-day into great conglomerate beds of rock structure, so that 

 one of the first lessons you learn on this charming spot clearly shows us that 

 fire and water have both done their part in producing the framework of the 

 scene around us. 



In order to understand the 'next part of our story I must tell you that 

 the history of the earth's crust, written upon its own leaves or strata, is divisible 

 into four volumes, each of which contains most valuable teachings of its origin 

 and progress, in the first volume are included all the formations between the 

 oldest sedimentary rocks, and those which you see lying before you in the Forest 

 of Dean, and comprising the formations called Primary or Palaeozoic rocks or 

 those containing the oldest forms of animal and plant life. The second volume 

 includes the Secondaiy or Mesozoic formations or those containing the middle 

 forms of life, some of the rocks of this period we travelled over to-day between 

 Gloucester and Ross, and others form the Cotteswold hills overlooking the 

 valley of the Severn, or ranging as chalk downs through Wiltshire. The third 



