@Clarke_Morledge and @BradKramer,
Yes, my columns deal with the American story, not the British story. There were “scriptural geologists” (Mortenson’s heroes) on both sides of the ocean, but the Americans were basically parroting the Brits–the same situation in mainstream geology as well. The USA was a scientific backwater (generally) until after the Civil War; most of the science taught here originated somewhere in Europe, and likewise for American views of science & the Bible.
Mortenson contends that (a) geological ages were the invention of “atheists and deists,” who doubted or denied the Bible and who were committed to metaphysical naturalism; (b) many Christians caved in to academic pressure (consciously or unconciously) and adopted the geological timescale of the sceptics, using ideas from Galileo and Bacon to justify that move; and (c) the Scriptural geologists, who resisted that move entirely, defended the historicity of Genesis and used their literal interpretation of it (Mortenson would probably say just Genesis, since he and other YECs are somewhat reluctant to say that they are “interpreting” the Bible at all) as the basis for an alternative geology.
Mortenson’s account is persuasive to very large numbers of Christians in America and also to a growing number of British evangelicals. (On the latter, see this A geologist looks at Creationism | Peddling and Scaling God and Darwin by geologist and Anglican minister Michael Roberts, one of the most incisive critics of the YEC view you will encounter.) The best antidotes are a deep and broad understanding of geology (which I do not posses), a deep and broad understanding of the Bible in its ANE context (here I’m better off than in geology, but obviously not an expert), and a deep and broad understanding of the history and philosophy of science. Very few lay people have any of these knowledge sets, and most pastors don’t either, though obviously many have studied biblical languages with experts more than most others have.
Since you’re looking specifically for criticisms of Mortenson’s historical claims, I’d look for books and articles by Davis Young and Michael Roberts. Both have excellent knowledge of relevant parts of the history of geology, and both know quite a bit of theology and hermeneutics as well. Most of their work is available only in print books or print journals. Perhaps the best single piece is print-only, Davis Young’s article in Christian Scholar’s Review about nineteenth century Christian geologists and their view of Scripture. I don’t have chapter and verse here at home, but if you contact me privately (tdavis AT messiah DOT edu) I can send it to you.
I don’t think anyone has actually written a step-by-step reply to Mortenson, but it would need to be lengthy and carefully nuanced, b/c many of the individual things he says are true. Geology (in the modern sense) was born in the Enlightenment, and many of its founders were not biblical Christians. A lot of 19th century Christian geologists did accept the great age of the earth, but (contrary to Mortenson) they did so b/c they drew their own conclusions from the evidence, not b/c they feared losing status. In America at least they had secure appointments at places like Yale or Amherst; they weren’t worried about losing their jobs or losing prestige, and (contrary to what Mortenson wants you to think) they took the Bible very seriously as history and they weren’t hesitant to bring the Bible into their public writings. They dismissed the ideas of the Scriptural geologists b/c they found them incredible in the face of the evidence, not b/c they dismissed the relevance of the Bible.