He knew the grey tide must already be at full flood on the other side.

Just beyond the nearest uphill trees she could see a gray tide.

Their speed was astonishing; they seemed to move over the ground like a grey tide.

As they started to run, the grey tide flowed in towards their feet.

And suddenly the Shadow Host that had hung back at the last came up like a grey tide, sweeping all away before it.

Of course, thus far the grey tide had spared the Sol system, but that couldn't last forever.

The grey tide had, after all, spared nothing else.

She whimpered, but the gray tide had already swept in and flooded her mind.

Like a big gray tide, the rains swept in, and the rains swept out.

The sitting-room faced the sea, whose tide, grey and shaggy, hissed not far off.