G8 NEWER PLIOCENE PERIOD. 



[Ch. VI. 



These marls arc sometimes gypseous, and belong to a great 

 argillaceous formation which stretches over a considerable part 

 of Sicily, and contains sulphur and salt in great abundance. 

 The strata of this group have been in some places contorted in 

 the most extraordinary manner, their convolutions often resem- 

 bling those seen in the most disturbed districts of primary clay 

 slate. 



But we wish, at present, to direct the reader's exclusive at- 

 tention to strata decidedly referrible to the newer Pliocene 

 era, and we have yet to mention the igneous rocks associated 

 with the sedimentary formations already alluded to. 



Volcanic Rocks of the Val di Koto. The volcanic rocks 

 occasionally associated with the limestones, sands, and marls 

 already described, constitute a very prominent feature through- 

 out the Val di Noto. Great confusion might have been ex- 

 pected to prevail, where lava and ejected sand and scoriae are 

 intermixed with the marine strata, and, accordingly, we find it 

 often impossible to recognize the exact part of the series to 

 which the beds thus interfered with belong. 



Sometimes there are proofs of the posterior origin of the lava, 

 and sometimes of the newer date of the stratified rock, for we 

 find dikes of lava intersecting both the marl and limestone, 

 while, in other places, calcareous beds repose upon lava, and 

 are unaltered at the point of contact. Thus the shelly lime- 

 stone of Capo Santa Crocc rests in horizontal strata upon amass 

 of lava, which had evidently been long exposed to the action 

 of the waves, so that the surface has been worn perfectly 

 smooth. The limestone is unchanged at its junction with the 

 igneous rock, and incloses within it pebbles of the lava*. 



The volcanic formations of the Val di Noto usually consist 

 of the most ordinary variety of basalt with or without olivine. 

 The rock is sometimes compact, often very vesicular. The 



some which lie obtained from the same localities, but I have met with no zoolo- 

 gists who could name the species. 



* This locality is described by Professor Iluilinann, Arcliiv fur Mineralo^ir. Xc. 

 Berlin, 13-Jl. 



