36 ROLLIN T. CHAMBERLIN 



very fragmentary, by itself suggests that they have been disturbed 

 and transported to a greater or less extent. On the contrary, the 

 human bones, so much less scattered as to indicate that they 

 belong to distinct individual skeletons, imply that they have 

 suffered much less disturbance. 



The history of the bones seems to unravel as follows : For a long 

 time during the Pleistocene there existed a marshy area of con- 

 siderable extent immediately to the west of the present location of 

 the spillway. Peat accumulated in the bog, forming layer c of the 

 upland section. In the course of its growth, various animal 

 remains of' the time became incorporated. The large vertebrates 

 were no doubt often mired, and left their bones in the bog. This is 

 a familiar process. 



During and following the accumulation of the bog and the 

 bones, the upper portion of the sandy formation that lies beneath 

 the peat (stratum b) became indurated to sandstone by the infil- 

 tration of iron oxide. At the same time it was stained black by 

 the decomposition products of the decaying organic matter that 

 lay over it. 



With further passage of time the large land vertebrates, one 

 after another, became extinct in the region. In the course of time 

 also man appeared in Florida. At some time subsequent to the 

 growth of the bog, probably as the result of a slight uplift, Van 

 Valkenburg's Creek and its branches, or their antecedents, cut 

 channels across the beach ridge and into the peat deposit, the two 

 forks apparently following essentially the courses which they hold 

 today. The drainage lines thus established cut, not only into the 

 Pleistocene bog deposits, but into the sands beneath. With the 

 draining of the bog and the adjacent land the movement of sand 

 by wind action was perhaps facilitated, and the dune formation 

 (layer d) which covers the old bog surface west of the spillway may 

 have been formed during the drainage stage. It is not incon- 

 sistent, however, to suppose that it was formed before the drainage 

 was established. 



Later came the stages of partial filling of the creek channel. 

 The first stage was occupied by the deposition of formation No. 2 

 of Sellards. The material for this formation was derived from the 



