I just remembered something else that I find interesting about this whole issue. Fitzroy found little support for any of his fundamentalist views amongst the officers of the Beagle. This suggests that amongst educated men even by 1830 it had been realised that Genesis does not stack up as a meaningful historical account, but should be read as an allegory. Fitzroy wasn't a fool though, he and Darwin would avidly read the latest volume of Lyell together as they arrived in the Beagle's ports of call (Darwin was having them shipped out), though Fitzroy must have found Lyell's conclusions utterly unpalatable.
Creationists like to fantasize that it was Darwin who turned people away from Biblical literalism, but people (most of them devout God-fearing people) were realizing that there were big problems with Biblical literalism (at least as it concerns natural history) as far back as the 1700's if not earlier, and by the mid 1850's (still before Darwin had published his famous book) the evidence was too overwhelming to ignore.
For example, by that time most geologists had realized that the geologic record was not consistent with a global flood. In 1857 Hugh Miller -- a creationist geologist -- wrote of his conclusions that at most, the Biblical flood was the embellished record of a local flood in the Mideast, since geology showed no signs of a global flood. On page 327 of his book, "The Testimony of the Rocks, he wrote:
"No man acquainted with the general outlines of Palaeontology, or the true succession of the sedimentary formations, has been able to believe, during the last half century, that any proof of a general deluge can be derived from the older geologic systems, -- Palaeozoic, Secondary [Mesozoic], or Tertiary."Similarly, in the 1700's many lines of evidence led to widespread doubt about the Bible's 6000-year chronology for the age of the Earth. By the mid 1850's estimates of millions of years were suggested, and the Earth has been known to be on the order of a billion or more years old since at least 1911. Calculations of the age of the Earth were converging on the true age as long ago as the 1920's -- for example: 4.0 billion years (Russell, 1921), 3.4 billion years (Rutherford 1929); 4.6 billion years (Meyer 1937); and 3 to 4 billion years (Starik 1937). The number hasn't changed appreciably since the 1940's, when it converged to 4.5 +/- 0.1 billion years due to advances in analytical equipment (thanks to the Manhattan project).
But, hey, I guess the modern-day literalists know better than to make the mistake of paying any attention to 300+ years of accumulated evidence, observations, and discoveries, eh?