At some later period either earthquake convulsion started the break which ultimately eroded and disintegrated into the great gorge through which the railway has brought us, or grinding glacier cut the pathway for us.
Here, on the right, is a tiny swinging foot-bridge over the river.
This is the beginning, the suggestion, for the vast suspension bridges that have allowed the world to cross the great North River from New York to Brooklyn, and that span great rivers and gorges elsewhere in the world.

Nay! scarcely the beginning.

That you find further up and deeper down in the High Sierras and their shaded and wooded canyons, where wild vines throw their clinging tendrils across from one shore to another of foaming creeks, and gradually grow in girth and strength until they form bridges, over which chipmunks, squirrels, porcupines, 'coons, coyotes, and finally mountain lions, bears, and even men cross with safety.

There is the _real origin_ of the suspension bridge.
But this is a miniature, a model, a suggestion of the big bridges.
It affords ready access to the house on the other side.

In winter, however, the boards are taken up, as the heavy snows that fall and accumulate might wreck it.
It is hard to realize that, a few months from now, when winter begins, this railroad must perforce cease its operations.