Theory of Formation of Sedimentary Deposits. 125 



ceases, other conditions remaining constant, one naturally 

 expects that the forms will spread from many centres 

 outward, or towards the land at least, and that during the 

 continued depression of that land area the sea may trans- 

 gress upon it and the material formed by the comminution 

 of the hard parts of these organic forms will form a series 

 of deposits resting directly upon the oldland. Such for- 

 mations are now being formed along parts of the 

 Florida coast at the present day. It seems quite prob- 

 able that such also, on a somewhat greater scale, may 

 have been the condition of affairs during Devonian time 

 when the corals, which Parks found with the bases 

 attached to an Archean boss, were living in the Hud- 

 son Bay basin, and such was the case in many other 

 localities. In the case of the example cited as occur- 

 ring at Kingston Mills, the fragments of the crinoid 

 stems are sometimes several inches in length. The 

 pebbles of the conglomerate with which these and the 

 Camoceras casts are associated vary in size up to about 

 two inches in diameter, and the fossils are found in the 

 beds not only quite close to the Archean, but also in the 

 upper beds some distance above it. That under these 

 conditions the forms were not comminuted suggests that 

 here at least the water must have been comparatively 

 quiet, and hence we may draw the not unnatural inference 

 that the waters were moderately deep. The calcareous 

 material was probably derived from the comminution of 

 organic forms elsewhere, or it may be in part a chemical 

 precipitate. 



A consideration of the foregoing propositions indicates 

 that a feature which one would expect to find in any 

 series of deposits is a zonal arrangement of the various 

 members. Not only may there be two lithological ex- 

 tremes and a mean of synchronous beds (or series of strata) v 

 but during the period of continuous depression and depo- 

 sition there may be formed a continuous band of each of 



