Such a journey would represent one of the most astonishing migrations ever undertaken - the Earth was then in the grip of the Ice Age, and much of its high northern and southern latitudes were desolate wastelands blasted by storms and blizzards.
And he needed whatever information he could get, because in the novel's fourth section - its astonishing centrepiece - he undertakes another of his epic reconstructions.
With the publication of Glen Greenwald's book No Place to Hide: Edward Snowden, the NSA, and the U.S. Surveillance State, there are going to be reams more written on the astonishing acts of electronic surveillance primarily undertaken by the NSA.
Rose (the astonishing Francesca Annis) has a scheme to put it to rights, recruiting older workers to undertake the dangerous cleanup and spare the younger ones.
The draft regulations would allow companies to undertake offshore exploration for oil and gas near the Great Blue Hole, an astonishing submarine sinkhole that was named a Unesco world heritage site in 1996.
They were just astonishing.
The transformation was astonishing.
The transformation is astonishing.
What an astonishing sentence.
Those are astonishing numbers.
