Other charts—and most significantly one in connection with the founding fifty million years ago of the vast dead city around us—showed all the present continents well differentiated. And in the latest discoverable specimen—dating perhaps from the Pliocene Age—the approximate world of to-day appeared quite clearly despite the linkage of Alaska with Siberia, of North America with Europe through Greenland, and of South America with the antarctic continent through Graham Land.
In the Carboniferous map the whole globe—ocean floor and rifted land mass alike—bore symbols of the Old Ones' vast stone cities, but in the later charts the gradual recession toward the antarctic became very plain.
The final Pliocene specimen showed no land cities except on the antarctic continent and the tip of South America, nor any ocean cities north of the fiftieth parallel of South Latitude. Knowledge and interest in the northern world, save for a study of coast lines probably made during long exploration flights on those fan-like membranous wings, had evidently declined to zero among the Old Ones.
Destruction of cities through the up-thrust of mountains, the centrifugal rending of continents, the seismic convulsions of land or sea bottom, and other natural causes was a matter of common record; and it was curious to observe how fewer and fewer replacements were made as the ages wore on.
The vast dead megalopolis that yawned around us seemed to be the last general center of the race—built early in the Cretaceous Age after a titanic earth buckling had obliterated a still vaster predecessor not far distant.
It appeared that this general region was the most sacred spot of all, where reputedly the first Old Ones had settled on a primal sea bottom. In the new city—many of whose features we could recognize in the sculptures, but which stretched fully a hundred miles along the mountain range in each direction beyond the farthest limits of our aërial survey—there were reputed to be preserved certain sacred stones forming part of the first sea-bottom city, which were thrust up to light after long epochs in the course of the general crumpling of strata.
VIII.
Naturally, Danforth and I studied with special interest and a peculiarly personal sense of awe everything pertaining to the immediate district in which we were. Of this local material there was naturally a vast abundance.
On the tangled ground level of the city we were lucky enough to find a house of very late date whose walls, though somewhat damaged by a neighboring rift, contained sculptures of decadent workmanship carrying the story of the region, much beyond the Pliocene map, whence we derived our last general glimpse of the prehuman world. This was the last place we examined in detail, since what we found there set upon us a fresh, immediate objective.