52 



HYATT ON THE TERTIARY SPECIES 



Section U.' 



The dip of the strata is quite irregular, considering the limited boundaries of the pits, 

 varying from 10" to 30° of inclination outwards on all sides of the central hill. 

 This elevation, to a certain exteiat, evidently took place before the formations of the 

 pits were entirely completed. This is shown by the pocket containing the PI. multiformis 

 and PI. discoideus shells in the New Pit, and also by a similar pocket in the East Pit. 



Formations m and a; 2 of 

 Section 9 were evidently de- 

 posited one upon the other 

 in the New Pit. The only 

 way to explain the appearance 

 of the wood-cut, after this, 

 is to imagine that the fold- 

 ing took place along the lines 

 of elevation. The wood-cut 

 represents a_ section at right 

 angles with the dip, so that 

 the folds run across the strike 

 • of the layers. 



Subsequent to the folding, a certain amount of denudation must have removed part 

 at least of the bed x 2, and the upper part of the bed m, in order to permit the deposition 

 of 71 0, and x 3. 



Whether the same tendency to fold continued, caused by the resumption of the 

 process of elevation on either side of x 3, and gave the basin-shape to n o, deepened the 

 folds on either side, but did not alter them otherwise, leaving x 3 a symmetrical 

 hollow, or saucer-shape, is doubtful. They seem to belong to the same system of folds as 

 X 2 and the want of x above is probably due to local denudation. On the face of the pit 

 on the north side of x 3, this is shown by the anticlinal bend in m, but even more 

 perfectly by the fact that n o, and m become exactly parallel farther to the north. 



Section 10 shows that some- 

 what similar conditions must 

 have obtained in the East Pit ~ ) 



at about the same time. Un- -""^ 



fortunately I had confused the '^ 



samples from x 1, with those '^^ 



from k, and consequently only 

 rely on my notes made upon 

 the detailed section. These 

 speak of trochiformis in two 

 places as prevalent, but not 

 abundant ; whether, therefore, 

 other fossils occurred with this 

 I cannot say. 



Here the bed x is in both cases a pocket — in one case in a fold, and in another evidently 

 occupying a hollow in an undisturbed clay layer. It is very evident that formation 



* These sketches are not drawn to any definite scale. 



Sectkpn 10.1 



