Devonian Series in SoutJnrestet'n Missouri. — JlersJw//. 297 
That the sandstone does not belong to the Ozark series is 
known from the fact of its passing across the upturned edges 
of slightly tilted layers of dolomite in some places in this 
region ; although generally no more than four inches in thick- 
ness, it is present over many square miles of territory, and is 
in contact with different layers of the dolomites in different 
places. Furthermore, in lithological composition it is entirely 
unlike any sandstone stratum in the Ozark series. As final 
proof of its belonging to the overlying series, I may state that, 
although this sandstone is nearly free from fossils, a few have 
been found in it having a distinctly Devonian facies. 
It will readily be seen that the four divisions of our series 
were deposited in the same body of water in immediately suc- 
ceeding periods of time ; and I should say that each member 
or division corresponds to a separate epoch of geologic time, 
as each certainly indicates slightly different conditions. From 
a study of the distribution of the series and of certain facts 
indicating very weak wave action in the body of water, and 
also from the nature of the deposits themselves, it is verj^ 
probable, nay almost certain, that they were laid down on the 
bottom of a broad shallow estuarine basin, occupying a posi- 
tion on the south side of the land mass which then existed 
through what is now central and southern Missouri, and ex- 
tending thence far to the northwest up the present Missouri 
valley. 
Through many ages the Ozark series had been subjected to 
subaerial erosion, and was almost completely baseleveled. A 
subsidence of the land mass or Missouri continent began some- 
time during the Devonian era, and, as soon as the lower por- 
tions of its broad shallow basin-like valleys had been sub- 
merged, the fauna of the surrounding seas invaded these estu- 
aries and formed limestones; and the streams which still 
flowed on the slowly diminishing land mass brought fine sedi- 
ment into the estuarine basins at their mouths. Deposits 
formed in such shallow basins of limited extent are found all 
around the borders of the Ozark uplift, except on the west 
where the proper horizon is not exposed and where the land 
mass continued. 
In the particular region under discussion the suljsidence 
lasted throughout the period, as is shown by the overlapping 
