226 The American Geologist. April, 1899 
the coal-making process on a grand scale was their dividing 
epoch. 
The two volumes in which are recorded the annals of these 
eras contain all that we at present know regarding the story 
of Pennsylvania. There maybe, indeed there probably is, a yet 
earlier volume, a pre-pala3ozoic one, but it is not yet publish- 
ed, its materials are not yet collected, and it cannot therefore 
be considered. 
In the earlier of the two volumes above mentioned we read 
accounts that reveal a condition of things so different from 
any now existing that the "oldest inhabitant" of the State may 
be pardoned for failing to recognize his home. If we could 
restore palaeozoic Pennsylvania with any approach to exact- 
ness we should have a series of successive geographies change- 
able as the views in a kaleidoscope. No one of these would in 
the least resemble the state as it now exists, but it would be 
possible to trace a process of evolution running through them 
and to discover some of its results even in the present topo- 
graphy. 
The palaeozoic age was long, very long, longer doubtless 
than all the time that has elapsed since it ended and in so vast 
an era it is of course impossible to present details. Still le»s 
is it possible to give at one view more than the merest outline. 
It must suffice to indicate in general terms what was going on 
in the region during the millions of years that flowed by as the 
period passed. 
If with the aid of the telescope of geology Ave try to sight 
across this long time-interval and realize or fill in the dim out- 
lines of the picture that is brought before our mental eye from 
that far-off" horizon we behold the water of a sea covering the 
greater part of what is now Pennsylvania. These waters were 
part of an immense Palaeozoic Mediterranean whose northern 
boundry was along the Canadian Laurentides, its western 
somewhere in the region of the RockyMountainsandits south- 
ern altogether unknown. Its eastern coast as nearly as can 
be determined lay long the line of the gneissic area in the 
southeast of the state for the most part, through Philadelphia, 
Chester, Lancaster and York counties. 
But the geologist does not pretend to lay down this coast- 
line with exactness or definiteness. The view is so distant and 
interrupted by so many intervening obstacles that only the 
