♦ 



390 University of California Publications in Geology [Vol. 7 



The bones in pocket no. 1 are not so well preserved as those 

 in pocket no. 2. This difference in preservation is rather difficult 

 to explain, since they accumulated at the same time and were 

 only a few feet distant. From the evidence obtained a sug- 

 gestion may be offered. In pocket no. 1 there are large lumps 

 of brittle asphaltic clay scattered among the bones, and at a depth 

 of fourteen feet the floor of the pit was nearly covered with this 

 clay, veined with asphalt-bearing bones. The fact that this clay 

 contains globules of asphalt and also~ has a brown color, which 

 is probably clue to the asphalt, leads us to believe that it was 

 deposited in juxtaposition to the tar pools. It is safe to say 

 that this pool was covered with water for a considerable length 

 of time, allowing the deposition of clay, and so affecting the 

 preservation of the bones. It is quite possible also that at inter- 

 vals the exudation of the tar was stopped and allowed these 

 pools to be capped with clay. Afterward the tar again came to 

 the surface and another pool was formed in which bones were 

 deposited. In pocket no. 2 the brown lumps of clay are not 

 found among the bones, and there is no evidence to indicate that 

 water once covered this pocket. 



Pocket no. 2 was the largest pocket of well-preserved bones 

 discovered. From within six feet of the surface to twenty-one 

 feet there was a solid mass of bones, the pocket varying in out- 

 line and narrowing toward the bottom. After the hard cover 

 was removed the matrix lying beneath was found to be very soft 

 and much tar oozed out at two or three points. Where the 

 tar was most abundant the bones were not so well preserved. 

 From a depth of ten to twenty feet the bones in this pocket were 

 of a light brown color and embedded in a fine sandy matrix with 

 a rather small percentage of tar. 



Pocket no. 3. as may be seen in plate 20, is much smaller 

 than either of the others, but contained many bones in a fine 

 state of preservation. Here bones were found at the surface 

 and from this down to fourteen feet. Some of the bones obtained 

 at the surface were poorly preserved, yet on the east side of the 

 pocket sloth material was found that was of a bright red color 

 and the bones as hard as Recent specimens. This pocket was 

 quite small and therefore only parts of skeletons seemed to be 



