The ground trembled again. Not alarmingly, but Babs' hold of his hand tightened a little. They continued to climb. They came out atop a small bare prominence which rose above the forest. Here they could see over the treetops in a truly extensive view. The mountains all about were clearly visible. Some were ten and some twenty miles away. Some, still farther, were barely visible in the thin haze of distance. But there was a thick pall of smoke hovering about one of the farthest. It was mushroom-shaped. At one time in human history, it would have seemed typically a volcanic cloud. To Cochrane and Babs, it was typically the cloud of an atomic explosion.
The ground shook sharply underfoot. Babs staggered.
Flying things rose from the forests in swarms. They hovered and darted and flapped above the tree-tops. Temblors did not alarm the creatures of the valley. But ground-shocks like this last were another matter.
A great tree, rearing above its fellows, toppled slowly. With ripping, tearing noises, it bent sedately toward the smoking, far-away mountain. It crashed thunderously down upon smaller trees. There were other rending noises. The flying things rose higher, seeming agitated. Echoes sounded in the ears of the two atop the hill.
There was another sharp shock. Babs gave a little, inarticulate cry. She pointed.
There was much smoke in the distance. Over the far-away cone, which was indistinct in the smoke of its own making—over the edge of the distant mountains a glare appeared. It was a thin line of bright white light. With infinite deliberation it began to creep down the slanting, blessedly remote mountainside.
The ground seemed to shift abruptly, and then shift back. Across and down the valley, five miles away, a portion of the stony wall detached itself and slid downward in seeming slow motion. Two more great trees made ripping sounds. One crashed. There was an enormous darkness above one part of the sky. Its under side glowed from fires as of hell, in the crater beneath it. There were sparkings above the mountaintop.
Very oddly indeed, the sky overhead was peacefully blue. But at the horizon a sheet of fire rolled down mile-long slopes. It seemed to move with infinite deliberation, but to move visibly at such a distance it must have been traveling like an express-train. It must have been unthinkably hot, glaring-white molten stone, thin as water, pouring downward in a flood of fire.
There was no longer a sensation of the ground trembling underfoot. Now the noticeable sensation was when the ground was still. Temblors were practically continuous. There were distinct sharp impacts, as of violent blows nearby.
Babs stared, fascinated. She glanced up at Cochrane. His skin was white. There were beads of sweat on his forehead.