rocks of Canada , whence the name Eozoön Canadense; so called from the Greek ēōs,
dawn, and zōon, an animal, as being the oldest life traceable in the past history of
the globe. Now generally regarded of mineral origin (Charles Morris, 1917)
Below is a photograph of a slabbed and polished specimen of Eozoon Canadense that is in a display cabinet on the third floor of the Matheson House Museum in Perth, Ontario. The specimen is said to be from North Burgess Township, Lanark County, Ontario. The specimen is about 7 inches (17 cm) wide. Eozoon Canadense, shown in the middle to upper half of the specimen, consists of the thin 1 mm thick alternating bands of green serpentine (with grains of spinel) and bands of grey dolomite.
The banding appears as raised ridges on one weathered edge of the specimen that is in the display cabinet. I suspect that most people, if they stumbled across a rock containing Eozoon would identify it as marble containing green serpentine, and might collect it for a rock garden.
What most who look at the specimen will not realize is that this rock has quite the history, and the one page commentary at the museum that describes the specimen and briefly sets out the controversy surrounding whether Eozoon is of organic origin or is inorganic and results from metamorphism, does not and cannot convey the magnitude of the controversy that surrounds Eozoon Canadense. Hundreds of scholarly articles in scientific journals (most published in the period from 1863 to 1899), numerous letters to the editor and four books have been devoted to Eozoon. It is hard to believe the controversy that Eozoon caused. Not just the leading geologists, paleontologists and mineralogists were involved. Leading biologists from England and Germany entered the fray. Besides the obstinance of the opposing parties, and their distinct lack of tact when attacking and dissecting opposing views and when questioning the qualifications of those asserting opposite views, there are various reasons for the controversy. The most important factor that led to the controversy is that Eozoon is found in Precambrian rocks that before the finding of Eozoon had been considered azoic – devoid of life.
A further factor that fueled the controversy is that Eozoon is found only in crystalline limestone showing varying degrees of metamorphism. Did metamorphism create the structure or modify an existing structure?
In addition there are five main types of Eozoon Canadense (all from the Precambrian rocks of the Grenville province of the Canadian Shield):
- the Burgess type, alternating bands of dark green serpentine with grains of spinel and thinner bands of grey dolomite, from North Burgess, south of Perth, Ontario
- the Calumet type, alternating bands of a light grey clinopyroxene and bands of calcite, from Grand Calumet along the Ottawa River
- the Côte St. Pierre type, alternating layers of white calcite and light green serpentine, from near Grenville, Quebec
- the Tudor type, parallel crescentic bands of calcite, from Tudor township in Hastings County, Ontario about 45 miles inland from the shore of Lake Ontario, in comparatively unaltered crystalline limestone
- the Huntingdon type, quartz bands alternating with bands of tremolite and calcite, from the Henderson Talc mine a few miles southeast of Madoc, in Huntingdon Township, Hastings County, Ontario
Further, not everyone that commented believed that the Tudor type and the Huntingdon type should even be classified as Eozoon. In addition, not everyone looked at all of the five main types of specimens, and few of the commentators looks at the specimens in the field. Most relied on thin sections and hand specimens provided by others.
The story started innocently enough. A few years before 1858 Dr. James Wilson, a physician and amateur geologist in Perth collected specimens from North Burgess township (just south of Perth) that he sent to his friend William E. Logan, Provincial Geologist for the Geological Survey of Canada. In 1858 somewhat similar banded specimens were collected by John McMullen of the Geological Survey from the Grand Calumet, an island along the Ottawa River, upstream from Ottawa. Logan thought the specimens strongly resembled fossils and displayed them at scientific meetings in the USA in 1859 and in England in 1862 as evidence of organic structures in Precambrian rocks, but met with little acceptance.
Logan (1863) in the Geology of Canada speculated that the Grand Calumet specimens “present parallel or apparently concentric layers, resembling the Stomatopora rugosa”, a common fossil, recognized the similar appearance between the specimens from North Burgess and Grand Calumet, and the differences in mineral composition between the specimens, and commented that “If both are to be regarded as the results of unaided mineral arrangements, it would seem strange that identical forms should be derived from such different compositions.” Below is the drawing of the “Supposed fossil from the Laurentian limestone, Grand Calumet” that appeared in Logan’s (1863) the Geology of Canada:
Below is a drawing of a specimen of Eozoon collected by Dr. Wilson of Perth, that appeared in Dawson’s 1875 book Life’s Dawn on Earth: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom.
In 1863 members of the Geological Survey of Canada found further specimens of Eozoon at Grenville, Quebec and nearby at Côte St. Pierre. Logan tried to get Elkanah Billings involved, but he declined, and the microscopic slides of the specimens were passed to J. William Dawson at McGill to study. Dawson arrived at the conclusion that they were “of animal nature”, a foraminifer which he named Eozoon Canadense, the dawn animal of Canada. Dawson and Logan enlisted the aid of Professor William Carpenter, an English naturalist and expert on marine zoology, notably in the lower organisms–foraminifera and crinoids. Carpenter agreed with Logan and Dawson. In 1865 each of Logan, Dawson and Carpenter, with a contribution from Sterry Hunt, published papers in the Journal of the Geological Society of London stating that Eozoon Canadense were giant fossil foraminifer.
The controversy started when William King and Thomas Rowney, mineralogy and chemistry professors at Queen’s College, Galway, Ireland, published on June 10, 1865 a letter to the editor of the London Reader, a weekly journal, asserting that Eozoon was “nothing more than the effect of crystallization and segregation.” Carpenter responded in the next issue of the London Reader questioning the qualifications and competence of both King and Rowney. King responded by letter published in the London Reader with a personal attack on Carpenter. So began a series of letters to the editor and articles in scientific journals by Logan, Dawson and Carpenter on one side and King and Rowney (and numerous others) on the other, each side attacking and dissecting opposing views (and the qualifications of those asserting opposite views).
In 1866 King and Rowney published an article in the Journal of the Geological Society of London setting out their investigations and why they believed Eozoon was of mineralogical origin.
In 1867 both Logan and Dawson reported on new specimens of Eozoon from (a) Tudor township in Hastings County, Ontario, that had been found in fairly unaltered crystalline limestone without serpentine, and (b) from southeast of Madoc. I suspect that Logan and Dawson expected that these new specimens would answer King and Rowney’s objections, but they merely added fuel to an acrimonious debate.
Notable articles opposing an organic origin were written by H. J. Carter, a marine zoologist, Otto Hahn and Karl Möbius, two German zoologists, and J. W. Gregory, a geologist with the British museum. Logan and Dawson did receive support (for example, Darwin, G.F. Matthews, Bigsby and Rupert Jones expressed support for their views), but there were many more people opposed to their views than supported them.
The debate raged until 1894 when specimens that were clearly formed by the metamorphism of limestone were found as blocks ejected from Mount Somma near Mount Vesuvius in Italy. These specimens were said to be identical to Eozoon. Limestone altered by magma and ejected from a volcano is not a fossil, and most geologists were convinced that the structure of Eozoon was therefore not a fossil. This did not deter Dawson, who, until he died, kept asserting Eozoon was of organic origin, denying that the specimens from Somma resembled in composition, mode of occurrence, or form and structure, the Eozoon of Canada.
The above is but a summary of the controversy. Charles F. O’Brien (1970) provides an entertaining eighteen page summary of the controversy, while Hofmann (1971) provides a seven page summary of the controversy, plus three plates showing specimens. Both are worth reading. O’Brien concentrates on the arguments made by the various parties, while Hofmann concentrates on the differences between the type specimens. O’Brien concluded that “Little doubt remains of the inorganic origin of Eozoon”, mentioning that “The active Eozoonist cause died with Dawson”. Hofmann concludes that Eozoon is inorganic, mentioning that the problem of the origin of the Burgess and Huntingdon types lies within the realms of metamorphic petrology and mineralogy, that for the Côte St. Pierre type, a “convincing case for an origin by contact metamorphism” was made, that the Grand Calumet type “appears to be a fracture-filling phenomenon” as does the Tudor type. Hofmann does note that the Huntingdon type has “a certain resemblance to lamellar stromatolites ...[but] this resemblance is only superficial... and the individual mineral bands are considerably thicker than in stromatolites”.
Despite both O’Brien and Hofmann concluding that Eozoon is inorganic, that is not the end of the tale. Fenton and Fenton (1952) provide an eight page summary of the Eozoon controversy and conclude “most mineralogists maintain the conservative view that the supposed fossil is the product of metamorphism; lumps of minerals and nothing more. A growing number of paleontologists conclude that the slightly metamorphosed masses are stromatolites of algal origin. ” In a later book Fenton and Fenton (1958) provide a two page summary of the Eozoon controversy and mention that “Dawson found fossils resembling Eozoon in rocks in Hastings County, Ontario. Not only were these eozoons virtually unmodified by heat, steam, or compression: they were undeniably related to structures that have come to be know as stromatolites... This relationship, however, did not immediately establish the eozoons as fossils.” This was because stromatolites at that time were not considered fossils, but inorganic concretions.
It was left to work in the early 1980's by Marika S. Bourque and other members of the Ontario Geological Survey to recognize and promote the Huntingdon type Eozoon, namely quartz bands alternating with bands of tremolite and calcite, from a few miles southeast of Madoc, and found in surrounding townships, as being of biogenic origin– silicified and recrystallized algal colonies. Bartlett and DeKemp (1987) comment “Eozoon canadense comprises several similar, but distinct morphologies. A biogenic origin for one of these forms, the “huntingdon” type, has recently gained general acceptance, largely due to the contribution of M.S. Bourque to the present study. This does not, however, imply an organic origin for the other Eozoon canadense forms...” R. M. Easton (1992), relying on Bourque and deKemp, commented “Eozoon canadense huntingdon is an algal-laminate stromatolite. Other E. canadense types, however, may not be biosedimentary in origin and should be regarded for the moment as pseudofossils...”
One is left to wonder whether the Tudor type and the other more metamorphosed types are also stromatolites. Fenton and Fenton (1952) comment:
“A few radicals– or are they true conservatives?– suspect that even the most highly metamorphosed masses are also fossils, but have been changed so greatly that their true nature appears only when banks or reefs are examined in the original rock. All factions agree on just one point: Eozoon is not a foraminifer, as Dawson and Carpenter tried to prove."
Christopher Brett
Perth, Ontario
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References
Bartlett, J .R. and DeKemp , E. A., 1987
Lithofacies, Stromatolite Localities, Metallic Mineral Occurrences, and Geochemical Anomalies associated with Carbonate Metasediments of the Burleigh Falls-Bancroft-Madoc Area, Southern Ontario. Ontario Geological Survey, Map. P.3079
Bourque, Marika S., 1981
Stratigraphy and Sedimentation of Carbonate Metasediments Within the Grenville Supergroup, Ontario Geological Survey, Summary of Field Work, 1981 , Miscellaneous Paper 100, 77-79
Bourque, Marika S., 1982
Stratigraphy and Sedimentation of Carbonate Metasediments within the Grenville Supergroup
in the Havelock-Madoc-Bancroft Area, Ontario Geological Survey, Summary of Field Work, 1982, Miscellaneous Paper 106, 89-91
Easton, R. M., 1992
The Grenville Province and Proterozoic History of Central and Southern Ontario, Chapter 19 in Geology of Ontario, Ontario Geological Survey Special Volume 4, Part 1, pages 715-904 at 796-797
Fenton, Carroll Lane and Fenton, Mildred Adams, 1952
Giants of Geology, Doubleday & Company, Inc., Garden City, New York
Fenton, Carroll Lane and Fenton, Mildred Adams, 1958
The Fossil Book: A Record of Prehistoric Life, Doubleday, New York
Hofmann, H. J., 1971
Precambrian Fossils, Pseudofossils and Problematica in Canada,
Geological Survey of Canada, Bulletin 189, 146 pages
Logan, W. E, 1863
Geology of Canada, Geological Survey of Canada, Report of Progress from its Commencement to 1863, Montreal, Dawson Brothers, 983 pages
O’Brien, Charles F., 1970
Eozoon Canadense “The Dawn animal of Canada”, ISIS, A Journal of the History of Science Society, Volume 61, No. 2, 206-223
Books Written on Eozoon
Dawson, J. William, 1875,
The Dawn of Life: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom
Dawson Brothers, Montreal, 239 pages
This book was also released in 1875 in a second edition of two thousand as:
Life’s Dawn on Earth: Being the History of the Oldest Known Fossil Remains, And Their Relations to Geological Time and to the Development of the Animal Kingdom
Hodder and Stoughton, London, England, 239 pages
https://books.google.ca/books?id=mQrWjgEACAAJ
Dawson, Sir J. William, 1888,
On Specimens of Eozoon Canadense and Their Geological and Other Relations.
Peter Redpath Museum, McGill University, Montreal, 106 pages
King, William and Rowney, Thomas Henry, 1881
An Old Chapter of the Geological Record with a New Interpretation: Or, Rock-metamorphism (especially the Methylosed Kind) and Its Resultant Imitations of Organisms: With an Introduction Giving an Annotated History of the Controversy on the So-called "Eozoon Canadense," and an Appendix
London: John Van Voorst, https://books.google.ca/books?id=ocq7AAAAIAAJ
Preface and introduction: pages i-lvii, plus 142 Pages of text and plates;
Pages ix - lvii summarize King and Rowney’s views of the papers on Eozoon written from 1858 to 1880
Hauer, Max, 1885,
Das Eozoon canadense. Eine micro-geologische Studis, 55 pages with 18 photographic plates. Leipzig, Germany.
