38 REV. G. R. HALL, ON 



opposite or northern extremity, and at a lower elevation, pass 

 along the declivity. 



Such are the terraced slopes of North Tynedale which I have 

 seen for myself; some of them bearing a very marked character, 

 and all of them deserving, perhaps, more than the incidental refer- 

 ence which has been hitherto given to a few examples. The dif- 

 ficult question of their origin, whether natural or artificial, or 

 partaking of both of these characters, now faces us, and I confess to 

 considerable difiidence in endeavouring to state fairly the various 

 theories that science and observation have put forward to account 

 for them, and the conclusions at which I have myself arrived. 



Natural Origin. — Here we enter on the domain of the geolo- 

 gist, and retire into the dim mysterious ages of the far-distant 

 past, which witnessed the gradual preparation of the earth's sur- 

 face by Divine power and wisdom for the requirements of human 

 existence. Above the present beach or sea-margin of our own 

 country, and along the shores of nearly all Western Europe, fol- 

 lowing the bays and recesses of the land, are, it is well known, 

 various ancient or raised beaches. It is supposed that these 

 terraces on our coasts and on the banks of estuaries prove either 

 an elevation of the land or a depression of the ocean, and the 

 former presence of tides and waves at these successive levels. 

 Sometimes a mere shelf or line on a hill side, of no greater mag- 

 nitude than the terraces of North Tynedale, attests the change of 

 relative height between former and existing sea-margins. With 

 respect, however, to these beaches or terraces, which are found 

 belting the slopes of inland valleys, unless we have reason to 

 consider them as estuaries in the seas of geological times, another 

 but similar agency has been suggested. They are held to give 

 evidence of previous water-levels, and seem to " point to a time 

 when the valley was occupied by a lake at that height, or when 

 the plain stood at that level, and before the river had worn its 

 channel down to its present depth." These long horizontal ter- 

 races or ledges of sand or gravel and silt have attracted much 

 attention during late years. Sir Chas. Lyell, it will be remem- 

 bered, speaking of the " changes of surface during and since the 



