These manifestly were what Roy had meant by pine-mats.

Here and there a fallen monarch lay riven or rotting.

Helen was presently struck with the silence of the forest and the strange fact that the horses seldom made any sound at all, and when they did it was a cracking of dead twig or thud of hoof on log.

Likewise she became aware of a springy nature of the ground.

And then she saw that the pine-mats gave like rubber cushions under the hoofs of the horses, and after they had passed sprang back to place again, leaving no track.