LINOSA AND ITS ROCKS 3 



whom I have been unable to consult), gives a page of description, with 

 considerable detail as to altitudes, etc. He makes mention of but 

 four volcanoes, but it is interesting to note that Calcara recognized 

 the two periods of vulcanicity to be described later, though his "tra- 

 chytic" rocks are shown by my observations and analyses to be 

 basaltic tuffs, and were evidently referred to the trachytes because 

 of their light color. 



The most recent, and the only modern, paper dealing with the ge- 

 ology is that of Speciale,' which is but a preliminary one, the second 

 part, which was to describe the petrography of the rocks, never having 

 appeared. In this two-page paper Speciale briefly describes the 

 general geology and several of the volcanoes, distinguishing between 

 those of tuff and of lava, the limits of which are given on his map. 



The last paper to be mentioned is that of D'Avezac,^ who gives a 

 general description, apparently based largely on the observations of 

 Captain Smyth prior to 1823. The geology is summarily treated, 

 but the history of the islet is discussed more fully, D'Avezac showing 

 that Linosa is the 'Kveixovaa of Ptolemy. 



Three maps of Linosa are available. The most satisfactory is 

 that found on Sheet 211 of the charts of the Italian Instituto Idro- 

 grafico, on a scale of i : 25,000, and which has been used as the base 

 of that which accompanies this paper. A second is found on the 

 Linosa and Lampedusa sheet (No. 193) of the British Admiralty, on 

 a scale of i : 25,100, and this sheet is of special interest because it 

 shows a view of the island from the southwest. The third is on 

 Foglio 265 of the topographic maps of the Instituto Geografico 

 Mihtare, the scale being i : 50,000. In all three the various volca- 

 noes are shown and many altitudes noted, though, between the 

 various maps, there are discrepancies as regards these and the names. 



General description. — The island of Linosa^ lies 20 miles north- 

 east of Lampedusa and about 59 southeast of Pantelleria. In form 

 it is nearly a square, the sides facing the cardinal points, with a length 

 east and west of about 3 kilometers and a breadth north and south of 



1 Op. cit., p. 165, with map. 



2 D'Avezac, lies de I'Afrique, Paris, 1885, p. 119. 



3 According to the British chart the Hghthouje is situated in Lat. 35° 52' N. and 

 Long. 12° 53' E. 



