1858.] GEMMELLARO SICILY. 505 



clay and sand. Volcanic currents from Etna more or less recent, all 

 augitic, — basalt, for the most part spheroidal and prismatic, a pleisto- 

 cene formation which has succeeded to that of the Terre Forte of 

 Catania, ancient prismatic and compact currents from Etna, recent 

 alluvium from San Tecla to Mascali, formed of volcanic felspathic 

 and augitic rocks — these elements constitute the topography of the 

 coast of Sicily from the mouth of the Simeto to the Onobola. 



From the Simeto to the Sciarra del Principe it is difficult to find 

 characteristic features in the recent alluvium, such as may mark the 

 lapse of time. The Sciarra del Principe, a volcanic current of 1669 ; 

 the shore at Catania, in which are seen pebbles of sandstone, recent 

 lavas, and fragmentary matter ; the Sciarra dell' Armisi ; that of the 

 Crocifisso of Lognina; the current of 1361,— these form the coast 

 to the neighbourhood of Lognina, and have been much changed from 

 their primitive aspect, these materials being daily used in the con- 

 struction of the mole at Catania. 



In the Scala di Lognina, from 4 decimetres to 1 metre above the 

 level of the sea, among great blocks of lava which form the shore, 

 one may observe a marine breccia, formed of small blocks of sand- 

 stone, augitic lava, and fragmentary matter, cemented together by a 

 calcareo-siliceous cement. 



From Lognina to Aci Castello, the volcanic currents which form 

 the shore present nothing of interest. Here begins the basaltic 

 current which came to the surface of the earth before the pleisto- 

 cene formation ; and as far as the Capo de' Molini, the study of the 

 coast is interesting in every respect. 



From the Pietra delle Sarpe, passing by the cotello to the cannito 

 of S. Giuseppe, the front of the volcanic current of 1169 has a very 

 compact structure, and forms a perpendicular cliff, showing in several 

 points, and for several metres in height, a zone of corrosion, depending 

 on the chemico-mechanical action of the sea-water. The lava, from 

 the upper part of which the blocks come that are seen along the 

 shore, shows itself with a very scoriaceous and irregular surface at 

 the height of from 8 decimetres to 1 metre above the level of the 

 sea, which makes one suppose that the igneous current must once 

 have touched the waters of the sea. Besides this, which is observed 

 in all lavas which are in contact with the waters, it appears that we 

 may also add the presence of many Se?'pulce, which indicate that the 

 current formerly touched the sea- water, and that it still preserves its 

 primitive configuration. 



From the west of the Cannito of S. Giuseppe to the basaltic rock 

 on which the ancient castle is built, one may see the same volcanic 

 current, which covers the spheroidal basalt, metamorphosed for 3 

 decimetres from its surface of contact. The south side of the rock, 

 formed entirely of spheroidal basalt and piperino, being in a state of 

 decomposition, falls continually, and presents nothing that is in- 

 teresting for examination. 



To the north of the rock the same lava of 1169 is excavated and 

 corroded at different heights ; and at 2 metres above the level of 

 the sea, we find adhering a coarse shelly sand, in which may be dis- 



