178 A. EF. Verrill—The Bermuda Islands; Geology. 
therefore probably belongs to the Walsingham Period; though per- 
haps to the latter part of it, for the peat is underlaid by older zolian 
limestones, 
It is unfortunate that careful microscopic examinations of this 
peat were not made, for it might have been possible to have identi- 
fied specifically some of the plants and other organisms, which may 
have differed from those in the modern peat bogs. 
The overlying beds of “coral crust” may have belonged to the 
Devonshire formation, and may indicate a subsidence, after the 
latter had been raised above the sea-level and hardened, for such 
materials do not appear to solidify in these waters, except when 
exposed more or less to the air. 
25. Fossils of the Marine Devonshire Formation, or Beach Lime- 
stones. 
The typical beach deposits of this period have been discussed 
above (see pp. 76-81), where it is also stated that the raised beach 
deposits may not all be of the same age, and that some of them may 
be very recent. But at present we have no positive means of deter- 
mining this in most cases, for the fossil shells are generally all living 
species. 
As the true Walsingham limestones were deposited at a time 
when the land was at a much higher level than now, we cannot hope 
to find, on dry land, marine deposits of that age. 
A deposit of fossiliferous rock containing Tellina, Lucina, ete., 
situated 16 feet below low-tide mark, found in the excavations made 
in Tomlin’s Narrows,* indicates by the nature of its solidification 
that it had been long exposed to the air and water above or between 
tides. It may represent a deposit of Devonshire beach-limestone 
made before the close of the first period of subsidence. But it may 
better be taken as one of the facts indicating that a small amount of 
subsidence must have occurred since the marine deposits were first 
elevated.+ It is probably of the same age as the “coral crust” in 
the Ireland Island section, fig. 58. These submerged deposits 
deserve much more investigation, 
In certain cases where extinct land shells of the Walsingham 
period have been found associated with red clay in cavities of the 
* See also, A. Agassiz, op. cit., 1895, p. 230. 
+ This would be in accordance with my belief that these Bermuda sands do not 
solidify into firm limestone except on exposure to the air. See p. 61. 
ee 
