A Star-Spangled Mastodon?

When I wrote about the NPS fossil proboscidean inventory, you may recall that I mentioned there was one Eastern record I wished I could have confirmed. I thought it was only fitting to shine a spotlight on it in conjunction with the anniversary of the event that made the park unit in question famous.

Fort McHenry National Monument and Historic Shrine, located in Baltimore, preserves Fort McHenry, famously bombarded by British ships September 13–14, 1814. Its resistance to the attack was commemorated in "The Star-Spangled Banner". That same year, workers preparing a well at the fort seem to have come up with... something, at least. Let's let pioneering American dentist Horace H. Hayden bring us up to speed. (Note the use of "M'Henry" for "McHenry", which complicates searching.)

"In Baltimore, these substances are found upon a bottom resembling marsh mud. At Fort M'Henry, in sinking a well, in the Star Fort in 1814, the workmen came upon a mass of carbonated wood, being part of a tree, as is supposed, lying across the well, at the depth of fifty feet or more, in a boggy marsh. This is two miles south of the granite ridge, or northern border of the great alluvial district. [Hayden 1820:105]"

"In digging a well in the star-fort of Fort M 'Henry, a tooth of the Mastodon (or Mammoth) was found at the depth of near sixty feet below the surface. [Hayden 1820:121]"

The bit about "mastodon (or mammoth)" takes us back to a time when the terms were used interchangeably. (Interestingly enough, the Baltimore edition of the Peale Museum opened in Baltimore in 1814, complete with Peale mastodon.) It is regrettable that the dentist Hayden did not provide details on the tooth, because for you and I distinguishing a mastodon tooth from a mammoth tooth is as elementary as distinguishing an egg carton (mastodon) from a washboard (mammoth). Unfortunately, such distinctions were not as widely appreciated in the early 19th century; after all, they didn't have egg cartons. It is not known whether Hayden was a party to the actual well-digging or received his information from someone else and never saw the objects in question, although I have not been able to find an earlier reference. He was not a well-digger by trade, but on the other hand he served as a surgeon during the Siege of Baltimore, so he was certainly in a position to have either observed the construction of the well or to have spoken to someone who had been on the scene.

The bombardment of Fort McHenry, found at Wikimedia Commons. Although "The Star-Spangled Banner" has several verses which are almost never used, none of them mention mastodons.

Naturally, I was excited when I first came across Hayden's report. I became increasingly disenchanted trying to follow it up. For one thing, the report appears to have vanished from the literature by the mid-19th century, without so much as a snide remark about its inaccuracy. It is mentioned in Rogers (1834) and Murray (1848), but is not included in more recent works where it would be relevant, such as Warren (1852) (which goes into great detail about the histories of other Baltimore proboscidean fossils), Uhler (1898 or 1900 [2020/09/15: tweaked citation date]), Maryland Geological Survey (1906), Hay (1923), and Bennett and Meyer (1952). Furthermore, the report of a mastodon or mammoth tooth 18 m (60 ft) below the surface at Fort McHenry conflicts with the most recent geologic mapping, which has Cretaceous sediments essentially at the surface, specifically the sand facies of the Patapsco Formation followed by the clay facies of the Arundel Formation at the purported depth of the tooth (Reinhardt and Crowley 1979). In the absence of an original original report, or the actual specimen, a few possibilities present themselves, with the least helpful discussed first:

1) The whole thing is a hoax; or, more benignly, an item along the lines of something someone made up to fill space in a newspaper. There is no evidence for this, and if we posit that the report is false, this becomes a short post indeed. (No cheering!)

2) It's a Cretaceous proboscidean. Somewhat mitigating against this exciting possibility are: 1) the complete absence of any proboscideans in North American rocks and deposits preceding the Neogene; 2) the complete absence of any other mammals closely related to or even resembling elephants in the Cretaceous; and 3) the complete absence of any other mammals remotely near elephant-size in other Cretaceous units. Bearing in mind these inconvenient absences, one might as well propose that mastodons had access to time travel.

With those out of the way, let's try some more serious hypotheses:

3) The "mastodon tooth" is actually a garbled reference to the wood. This could happen easily enough, say if two workmen remembered pulling up something from around 15 to 18 m (50 to 60 ft) down, but differed on the details. One man's chunk of wood could become another man's mastodon tooth, if we propose that the second man did not get a clear look at the object (and maybe had recently visited Peale's museum).

4) The "mastodon tooth" was a real object distinct from the wood, but not a mastodon tooth. What if a concretion, or a plain old rock, or a true fossil of some other sort was pulled up, and the identifier thought it looked kind of like a mastodon tooth?

5) The mapping of Fort McHenry's subsurface as only Cretaceous is inaccurate, or overly simplified. For example, given we're in a fluvial-to-estuarine system, could the well have been within a buried channel? It is interesting to note that Uhler (1898 or 1900) named a unit, the McHenry Formation, for recent sedimentary beds derived from marsh deposits. These marshes supported plants including bald cypress and white cedar, which left behind stumps and logs. The McHenry Formation (which did not catch on and is essentially unknown today) was described as composing "the upper part of the Fort McHenry plateau", with stump beds "adjoining the lands of the United States government at Fort McHenry" (Uhler 1898 or 1900:395). (This is all rather like the "Walker Interglacial Cypress Swamp" of nearby Washington.) It is noteworthy, though, that Uhler could find no mineralized fossils in the McHenry Formation. It is also noteworthy that the thickest instance he could find of this unit was 7 m (23 ft), and even with 1.5 to 2.4 m (5 to 8 ft) of surficial sand, soil, and gravel above, that's only halfway to 18 m (60 ft). For the wood itself, there is no great need to place it in Quaternary sediments; the Potomac Group, which includes the Patapsco and Arundel formations, is known for paleobotanical fossils.

6) The object is indeed a mastodon tooth, but it was actually at a higher level in the wall of the well, from which it became dislodged during the work and happened to be recovered when the well was about 18 m (60 ft) deep. We can combine this with #5: what if the well site passed through a Quaternary deposit on the order of 5 to 6 m (16 to 20 ft) thick or so, with the mastodon tooth within this before falling to the lower level?

If we eliminate #1 as untestable with our current knowledge and #2 for violating everything known about proboscidean distribution, we're left with four possibilities of some plausibility. I think #5 in its simplest form is least likely: it would require that the mappers somehow missed a Quaternary deposit at least 18 m (60 ft) thick. While I'd certainly like this to be #6, there is no obvious reason that it could not be #3 or #4.

References

Bennett, R. R., and R. R. Meyer. 1952. Geology and ground-water resources of the Baltimore area. Maryland Geological Survey, Baltimore, Maryland. Bulletin 4.

Hay, O. P. 1923. The Pleistocene of North America and its vertebrated animals from the states east of the Mississippi River and from the Canadian provinces east of longitude 95 degrees. Carnegie Institution of Washington, Washington, D.C. Publication 322.

Hayden, H. H. 1820. Geological essays; or an enquiry into some of the geological phenomena to be found in various parts of America and elsewhere. J. Robinson, Baltimore, Maryland.

Maryland Geological Survey. 1906. Pliocene and Pleistocene. The Johns Hopkins Press, Baltimore, Maryland. Systematic Report 3.

Murray, H., revised by T. G. Bradford. 1848. The encyclopædia of geography: comprising a complete description of the Earth,physical, statistical, civil, and political; exhibiting its relation to the heavenly bodies, its physical structure, the natural history of each country, and the industry, commerce, political institutions, and civil and social state of all nations. Volume III. Lea and Blanchard, Philadelphia, Pennsylvania.

Reinhardt, J., and W. P. Crowley. 1979. Geologic map of the Baltimore East quadrangle, Maryland. Maryland Geological Survey, Baltimore, Maryland. Quadrangle Geologic Map. Scale 1:24,000. (here or here [no download, but a clear preview without such an investment in file size])

Rogers, H. D. 1834. Report on the geology of North America, Part I. Report of the Fourth Meeting of the British Association:1–66.

Uhler, P. R. Variously given as 1898 or 1900. Preliminary notice of a recent series of geological accumulations, the McHenry Formation. Transactions of the Maryland Academy of Sciences 1:395–400.

Warren, J. C. 1852. The Mastodon Giganteus of North America. John Wilson and Son, Boston, Massachusetts.