"276 NICOLAUS STENO 



[Plate XI] 



The last six figures, while they show in what way we infer the six 

 distinct aspects of Tuscany from its present appearance, at the same 

 time serve for the readier comprehension of what we have said 

 about the earth's strata. The dotted lines represent the sandy strata 

 of the earth, so called from the predominant element, although vari- 

 ous strata of clay and rock are mixed with them ; the rest of the 

 lines represent strata of rock, likewise named from the predominant 

 element, although other strata of a softer substance are sometimes 

 found among them. In the Dissertation itself I have explained the 

 letters of the figures in the order in which the figures follow one 

 another : here I shall briefly review the order of change. 



Figure 25 shows the vertical section of Tuscany at the time when 

 the rocky strata were still whole and parallel to the horizon. 



Figure 24 shows the huge cavities eaten out by the force of fires 

 or waters while the upper strata remained unbroken. 



Figure 23 shows the mountains and valleys caused by the break- 

 ing of the upper strata. 



Figure 22 shows new strata, made by the sea, in the valleys. 



Figure 21 shows a portion of the lower strata in the new beds 

 destroyed, while the upper strata remain unbroken. 



Figure 20 shows the hills and valleys produced there by the 

 breaking of the upper sandy strata. 



