MEXICAN BOtJJIDAEY LINE. 115 



9. Crystalline quartz, with black tourmaline. — Near the dividing ridge of the Cordilleras; 

 east from San Diego. 



10. Feldspathic granite, with mica in large plates. The locality south from No. 1 of this 

 series, and belonging to the same (dividing) range. 



VIII. — Specimens from the eastern slope of the Cordilleras. 



1. Coarsely crystalline granite, with much mica and feldspar. — Lower California. 



2. Similar to the last, but with a less proportion of feldspar. — Lower California, near the 

 boundary line. 



3. Talcose slate, with Anthophyllite. 



4. Quartz in veins in the talcose slate. 



IX. — Specimens from the isolated mountains in the great plain of the Cordilleras, near the mouth 

 of the Gila, on the tvest side of the Colorado River. 



1. Syenitic rock, composed of hornblende and feldspar. 



2. Similar to the last, but finer grained. 



3. A granitic mass, composed of quartz, feldspar, and mica, with black tourmalines. 



4. A granitic mass, consisting chiefly of quartz with laminas of white mica The quartz con- 

 tains garnets. 



5. Gneiss or mica slate, finely granular and laminated. 



6. Epidote rock ; crystalline. 



7. Epidote with talc; (two specimens;) the talc in thin minute scales, and the epidote finely 

 granular. 



8. Epidote and talc; the epidote granular, but arranged in laminae. 



IX. — Miscellaneous specimens not numbered. 



Specimens designated as follows : 



" August 25," compact and amygdaloid traps. 



"August 29," marked as the lower stratum, is amygdaloid, having the appearance of fine 

 volcanic ashes, loosely cemented, and containing a few cavities filled with crystalline matter, 

 and others empty. 



" September IG," volcanic tuff. 



" September 17," green quartz in a cavity of amygdaloid. 



" September 30," specular iron ore connected with volcanic rocks. 



" October 7," reddish, porphyritic lava. 



""November 8, Mount Carmel," coarse syenitic aggregate. 



" November 10," reddish vesicular porphyry. 



"JVIareh 2, 1852," siliceous rock, apparently indurated trap tuff. 



"March 26, 1852," granitic lava, or trap tuff, with crystals of feldspar, mica, &c. 



" Summit of San Luis Mountains," an indurated tufaceous mass, with cavities lined with 

 quartz. 



" Mouth of Guadaloupe river," semi-metamorphic red shale. 



