to BUREAU OF AMERICAN ETHNOLOGY fBtTLL. 52 



Tliis specimen is a rounded piece of brown ferruginous earth, which 

 has evidently existed as a unit and been exposed to wind or water 

 transportation. Its outer surface is coated with small, rounded 

 particles and grains of quartz, plagioclase, pyroxene, magnetite, and 

 limestone, which are embedded in the fine, earthy material of the 

 specimen proper. The earth itself consists of argillaceous material 

 and fragments of quartz, plagioclase, pyroxene, hornblende, mag- 

 netite, and zircon. The darker-brown, ferruginous areas, which are 

 distributed irregularly through the specimen, are similar in composi- 

 tion except for the pronounced accumulation of limonitic material, 

 which is evidently the cementing material. Here and there in the 

 broken specimen long, canal-like cavities were observed, which evi- 

 dently mark the course of grass roots that have now disappeared. 

 On immersion in water this earth crumbles to a fine brown mud. 

 Its water solution gives a strong cliloride reaction when tested with 

 silver nitrate. 



No. 263709. Specimen label. ''Locality: About jive miles north 

 of Miramar. Bluff of Chapadmalean and Ensenadean. Material: 

 Tierra Cocida from a fogon or fireplace 4 f^^^ ahove heach in situ in 

 the Chapadmalean. B. W. 2 June, 1910." 



A light-brown, fine, evenly grained earth wliich consists of micro- 

 scopic grains, averaging 0.1 mm. in diameter, of quartz, plagioclase 

 (albite, oligoclase), a httle biotite and hornblende. Glass is also 

 present but appears decomposed and no longer clear. Argillaceous 

 material is abundant. Finely crystalline aggregates of a low-refract- 

 ing substance, possibly opal, were observed in several parts of the 

 specimen. A uniaxial negative substance of medium birefringence 

 and refractive index about 1.55 was encountered in the powder 

 section, but was not identified with certainty. This earth crumbles 

 and breaks down into mud when immersed in water. Its water 

 solution gives a strong cliloride reaction when treated with sUver 

 nitrate. 



The earth was heated with graphite to 1,300° for 30 minutes and 

 then held at 1,100° over night. The product was a dark-green glass, 

 in which microscopic fragments of the original mmerals were stiU 

 visible. An unusual amount of hematite had crystallized from the 

 melt; also occasionally a minute silicate microlite wliich was too fine 

 for satisfactory determmation. In a second experiment a portion 

 was heated to 1,300° with graphite. After fusion more material 

 was addetl and the whole mass reheated to 1,300°. This was repeated 

 several times. FmaUy the glass was crushed, mixetl with graphite, 

 heated to 1,300° for 40 minutes and then held at 1,000° over night. 

 The resulting glass was dark-green in color and contained occasional 

 traces of the origuial mineral fragments. In addition there were 

 present numerous clusters of microlites of fairly strong birefringence 



