In the decadent sculptures there were signs of thinner vegetation everywhere, and of a decreased country life on the part of the Old Ones. Heating devices were shown in the houses, and winter travelers were represented as muffled in protective fabrics. Then we saw a series of cartouches – the continuous band arrangement being frequently interrupted in these late carvings – depicting a constantly growing migration to the nearest refuges of greater warmth – some fleeing to cities under the sea off the far-away coast, and some clambering down through networks of limestone caverns in the hollow hills to the neighboring black abyss of subterrene waters.

In the end it seems to have been the neighboring abyss which received the greatest colonization. This was partly due, no doubt, to the traditional sacredness of this special region, but may have been more conclusively determined by the opportunities it gave for continuing the use of the great temples on the honeycombed mountains, and for retaining the vast land city as a place of summer residence and base of communication with various mines. The linkage of old and new abodes was made more effective by means of several gradings and improvements along the connecting routes, including the chiseling of numerous direct tunnels from the ancient metropolis to the black abyss – sharply down-pointing tunnels whose mouths we carefully drew, according to our most thoughtful estimates, on the guide map we were compiling. It was obvious that at least two of these tunnels lay within a reasonable exploring distance of where we were – both being on the mountainward edge of the city, one less than a quarter of a mile toward the ancient river course, and the other perhaps twice that distance in the opposite direction.

The abyss, it seems, had shelving shores of dry land at certain places, but the Old Ones built their new city under water – no doubt because of its greater certainty of uniform warmth. The depth of the hidden sea appears to have been very great, so that the earth's internal heat could ensure its habitability for an indefinite period. The beings seemed to have had no trouble in adapting themselves to part-time – and eventually, of course, whole-time – residence under water, since they had never allowed their gill systems to atrophy. There were many sculptures which showed how they had always frequently visited their submarine kinsfolk elsewhere, and how they had habitually bathed on the deep bottom of their great river. The darkness of inner earth could likewise have been no deterrent to a race accustomed to long antarctic nights.

Decadent though their style undoubtedly was, these latest carvings had a truly epic quality where they told of the building of the new city in the cavern sea. The Old Ones had gone about it scientifically – quarrying insoluble rocks from the heart of the honeycombed mountains, and employing expert workers from the nearest submarine city to perform the construction according to the best methods. These workers brought with them all that was necessary to establish the new venture – Shoggoth tissue from which to breed stone lifters and subsequent beasts of burden for the cavern city, and other protoplasmic matter to mold into phosphorescent organisms for lighting purposes.

At last a mighty metropolis rose on the bottom of that Stygian sea, its architecture much like that of the city above, and its workmanship displaying relatively little decadence because of the precise mathematical element inherent in building operations. The newly bred Shoggoths grew to enormous size and singular intelligence, and were represented as taking and executing orders with marvelous quickness. They seemed to converse with the Old Ones by mimicking their voices – a sort of musical piping over a wide range, if poor Lake's dissection had indicated aright – and to work more from spoken commands than from hypnotic suggestions as in earlier times. They were, however, kept in admirable control. The phosphorescent organisms supplied light with vast effectiveness, and doubtless atoned for the loss of the familiar polar auroras of the outer-world night.

Art and decoration were pursued, though of course with a certain decadence. The Old Ones seemed to realize this falling off themselves, and in many cases anticipated the policy of Constantine the Great by transplanting especially fine blocks of ancient carving from their land city, just as the emperor, in a similar age of decline, stripped Greece and Asia of their finest art to give his new Byzantine capital greater splendors than its own people could create. That the transfer of sculptured blocks had not been more extensive was doubtless owing to the fact that the land city was not at first wholly abandoned. By the time total abandonment did occur – and it surely must have occurred before the polar Pleistocene was far advanced – the Old Ones had perhaps become satisfied with their decadent art – or had ceased to recognize the superior merit of the older carvings. At any rate, the aeon-silent ruins around us had certainly undergone no wholesale sculptural denudation, though all the best separate statues, like other movables, had been taken away.

The decadent cartouches and dadoes telling this story were, as I have said, the latest we could find in our limited search. They left us with a picture of the Old Ones shuttling back and forth betwixt the land city in summer and the sea-cavern city in winter, and sometimes trading with the sea-bottom cities off the antarctic coast. By this time the ultimate doom of the land city must have been recognized, for the sculptures showed many signs of the cold's malign encroachments. Vegetation was declining, and the terrible snows of the winter no longer melted completely even in midsummer. The saunan livestock were nearly all dead, and the mammals were standing it none too well. To keep on with the work of the upper world it had become necessary to adapt some of the amorphous and curiously cold-resistant Shoggoths to land life – a thing the Old Ones had formerly been reluctant to do. The great river was now lifeless, and the upper sea had lost most of its denizens except the seals and whales. All the birds had flown away, save only the great, grotesque penguins.

What had happened afterward we could only guess. How long had the new sea-cavern city survived? Was it still down there, a stony corpse in eternal blackness? Had the subterranean waters frozen at last? To what fate had the ocean-bottom cities of the outer world been delivered? Had any of the Old Ones shifted north ahead of the creeping ice cap? Existing geology shows no trace of their presence. Had the frightful Mi-Go been still a menace in the outer land world of the north? Could one be sure of what might or might not linger, even to this day, in the lightless and unplumbed abysses of earth's deepest waters? Those things had seemingly been able to withstand any amount of pressure – and men of the sea have fished up curious objects at times. And has the killer-whale theory really explained the savage and mysterious scars on antarctic seals noticed a generation ago by Borchgrevingk?

The specimens found by poor Lake did not enter into these guesses, for their geologic setting proved them to have lived at what must have been a very early date in the land city's history. They were, according to their location, certainly not less than thirty million years old, and we reflected that in their day the sea-cavern city, and indeed the cavern itself, had had no existence. They would have remembered an older scene, with lush Tertiary vegetation everywhere, a younger land city of flourishing arts around them, and a great river sweeping northward along the base of the mighty mountains toward a far-away tropic ocean.

And yet we could not help thinking about these specimens – especially about the eight perfect ones that were missing from Lake's hideously ravaged camp. There was something abnormal about that whole business – the strange things we had tried so hard to lay to somebody's madness – those frightful graves – the amount and nature of the missing material – Gedney – the unearthly toughness of those archaic monstrosities, and the queer vital freaks the sculptures now showed the race to have – Danforth and I had seen a good deal in the last few hours, and were prepared to believe and keep silent about many appalling and incredible secrets of primal nature.