XI 147 



from all that appears, suspect that any marked fold of 



<>ck* U contained in the section. And yet on 



reaching b we should at once perceive that we were 



standing on the centre of an arch, saddle, or anticline, 



ttntta omrrd in an rch or A 



and that if we ^ wards t we should cross the same 



strata over again. Or, on the other hand, were we to 

 traverse a succession of strata dipping continuously 

 away from us, as from a to A in Fig. 45, and to come at 

 last to a flattening of them and the commencement of a 

 dip in the opposite direction, we should know that in 

 this case the rocks had been folded into a basin, trough, 

 or sync-line. 



The concealment of the central portion or axis of the 

 fold where, on a small scale, as in the cases I have 



ho 



supposed, of the rocks may be seen, 



does not make any difference in the interpretation to be 

 put upon the contrary dips at a and . in Figs. 44 and 45. 

 Indeed, in nature it is comparatively rare to see the actual 

 central bending of the strata. In almost all cases, except 



