“Yeah. They’re primarily schists and gneisses. The rocks were formed from pre-existing igneous and sedimentary rocks during mountain-building events in the deep past. A gneiss is what we call granitic rocks which have been exposed to later episodes of metamorphism, and—”

“I know. Go on.”

“Sorry. Well, we know that what’s exposed here is just the top of a much deeper layer. The rocks extend thousands of feet down from the surface and form the basement of the North American continent.”

“The basement?”

He nodded. “Rocks of that age and character underlie most of the continent. But it’s only where they have been exposed, like here, that we can study them…”

Monica knew a little about plate tectonics. She knew that the continents rode like rafts of granite, on the plates that slid on currents in the viscous molten rock that lay beneath. The younger rocks of the ocean floors, gabbro and basalt, were in time subducted — dragged back into the interior of the Earth, to be melted and reborn. But the ancient rocks of the continents, riding above, survived.

And now it looked as if, here and elsewhere, the Moonseed might reach those foundation rocks, the granite core of the continent itself, through this immense wound of rock and strata.

This is not good, she thought. Not good at all.

Well, then, we must do something about it. But what the hell she had no idea.

Scott took her arm, and led her back towards the car.

Scott started talking to her about the river ride she was going to have to take if she wanted to get any closer to those old Precambrian rocks. It meant a descent of five or six thousand feet, a rise in temperature of maybe twenty degrees. She calculated whether she would have the strength to undergo such a trip. And at the same time, she started to figure what she should tell the President, and how.

A black hole rocket engine, firing wildly in the ruins of Venus. Now, what was the meaning of that?

Strangeness. Too much of it, for one lifetime.

The sunset crept on them. The colours deepened to rust, mile-long shadows flooding at perceptible speed across the land, and they walked back to the car.

2

Henry was flown, mostly at low altitude under the ash clouds, the length of Britain.

Once, most of Britain was covered by a shallow ocean, which deposited gigantic chalk layers over the whole country. But then Britain tipped up. And the ice came, scraping most of the chalk off the top half of the island.

Now, as he travelled south from Scotland, he traversed younger and younger landscapes: billion-year-old gabbros and granites and basalts in Scotland, belts of successively younger sedimentaries as he came down through England, until he reached the youngest of all, the marine Pleistocene clays and sands around London, less than sixty million years old.