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the drifted remains of Walchia piniformis, Noeggerathia cuneifolia, 
Ulimannia selaginoides, and other plants of Neozoic affinities, are 
left, sometimes in sufficient quantity to,form thin seams of lignite 
or of coal. Then came a still more rapid subsidence ; the sea 
itself gained admittance, and, with it, came a few marine organisms, 
modified successors of those living in the previous Carboniferous 
times. But lagoon conditions speedily supervened, and precipi- 
tations of dolomite ensued in consequence. In this way the 
Magnesian Limestone Series was formed. 
Then followed a marked change of conditions, which may, 
possibly, have occupied considerable time. Mr. Howell has 
shewn that, in the north-east of England, much of the Magnesian 
Limestone there is missing beneath the strata next above; and the 
same feature is noticeable, though in a lesser degree, in the area 
specially under notice. Here, if anywhere in the series, is there 
an indication of the break between the upper series and the lower. 
A return to the old conditions of inland seas followed the 
temporary marine conditions. Red shales, saturated with iron, 
with carbonate of magnesia, with sulphate of lime, and, locally, 
with rock salt, were spread out with considerable uniformity over 
very large areas, their deposition being preceded by that of a band 
of shingle. In these shales mica was deposited in abundance, in 
which respect they differ from the beds below the Magnesian 
Limestone Series. During the later part of their deposition 
occasional sheets of micaceous sand were mingled with the sedi- 
ment; and, as time went on, the relative quantity of sand increased, 
until, eventually, the lake was shallowed up almost entirely, 
and was only submerged completely during seasons of unusual 
wetness. The sandstones thus presented all the characteristic 
indications of deposits accumulated under shallow-water conditions. 
In addition to the evidence effected by traces of suncracks, there 
are shale galls, pseudomorphs of rock salt, numerous footprints of 
air-breathing vertebrata (amphibio-reptilian) as well as the trails 
left by various other animals. 
It is evident that the physical conditions changed slightly now 
and then, prevalent shallow-water conditions giving place occasion 
