Washington — Catalan Volcanoes and their Rocks. 235 



Classification. — The calculated norms of the five rocks 

 analyzed are given below, the ratios being omitted. It is seen 

 that the specimens from Llora and La Garrinada fall in the 

 subrang monchiquose (III. 6. 2.4), while those from Las Planas, 

 Cruzcat, and Montsacopa fall in limburgcse (IIL6.3.4), the 

 difference in rang depending on slight differences in the 

 amounts of the alumina and the alkalies. This is shown in 

 the norms by the distinctly higher anorthite and lower albite 

 or nephelite in the last three. It cannot justly be said that 

 the differences are very significant, and as it seems probable 

 that the rocks are for the most part in limburgose, they may 

 be referred to collectively as monchiquose-limburgose. 



II III IV V VI 



Or 15-57 12-79 11-12 13-90 13\34 



Ab 10-22 12-58 15-20 8'64 13'86 



An 10-84 11-95 14-18 14'73 16-12 



Ne 12-92 11-08 6-82 12-07 9"51 



Di 19-17 23-76 22-02 24-18 21-03 



01 17-19 8-68 14-10 10-49 9"98 



•Mt 4-18 4-64 5-34 4"64 6'73 



II 8-21 8-66 9-42 7*75 8-06 



Ap 1-68 1-68 1-34 1-34 1'6S 



Rest -79 -68 -47 1'53 '35 



100-77 99-70 100-01 99-27 100-66 



Symbol 1II.6.2.4 III.6.2.4 III.6.3.4 III.6.3.4 III.6.3.4 



II. Monchiquose, Llora. 



III. Monchiquose, La Garrinada. 



IV. Limburgose, Las Planas. 

 V. Limburgose, Cruzcat. 



VI. Limburgose, Montsacopa. 



Occurrence. — This seems to be the most abundant rock type 

 in the district, being represented both in flows and at the 

 cones. Among the former the following localities may be 

 mentioned : the flow from Bana de Boch, below the Chapel of 

 Sant Medir, near Llora; the end of the extensive flow from 

 Puig Montcal, collected at Domeny, but not very fresh ; and 

 the extensive flow to the southwest of Olot, as at San Esteban 

 le Bas, San Feliu de Pallarols, and the quarries in the valley 

 of the Amer at Las Planas. Among the cone occurrences may 

 be named : the compact lavas from Cruzcat and from the sum- 

 mit of La Garrinada, and the scoriaceous ones from Montolivet, 

 Montsacopa, Bisaroca, Puig Costa, and others. The lava field 

 of Bosch de Tosca is also made up largely of this type, and 

 the dike found 3 kilometers from Olot, on the road to Santa 



