William Edmond Logan assumed his duties as the first head of the Geological Survey of Canada in June 1843. Two previously overlooked field notebooks provide new insight into his first field project that summer: measurement of the "Joggins section," a classic Carboniferous locality in Nova Scotia. Inspired by reports of 40-foot-tall fossil trees, Logan spent five days measuring 14 570 feet 11 inches of strata exposed along the shore of the Bay of Fundy. Widely regarded as a meticulous, bed-by-bed measured section, closer examination reveals that many thickness values were calculated using paced distances. Realizing that his measured section was too detailed for scientific journals of the day, Logan published his work in a relatively obscure government publication where it went largely unnoticed for nearly a decade. Unaware of Logan's measured section, John William Dawson and Charles Lyell visited Joggins in 1852 and measured the section for themselves. Dawson later stated that the two sections contain only minor differences, but careful comparison shows that they have radically different descriptions and measurements for even the most distinctive beds. Dawson disguised these discrepancies in post-1855 editions of his book Acadian Geology by rewriting much of the measured section and abandoning many of his own observations. Although over 200 subsequent Joggins studies build upon these measured sections, the present study represents the first detailed examination of the two historical sections and reveals previously unknown discrepancies between two of the most important early geologic studies undertaken in Nova Scotia.
RÉSUMÉWilliam Edmond Logan est devenu le premier responsable de la Commission géologique du Canada en juin 1843. Deux carnets de travaux sur le terrain, précédemment négligés, fournissent un nouvel éclairage sur son premier projet sur le terrain cet été-là : le mesurage du « stratotype de Joggins », un secteur carbonifère classique en Nouvelle-Écosse. Inspiré par des comptes rendus de la présence d'arbres fossiles de 40 pieds de hauteur, Logan a consacré cinq jours à mesurer 14 570 pieds 11 pouces de strates affleurant le long du rivage de la baie de Fundy. Un examen plus attentif de l'endroit, largement considéré comme un stratotype méticuleusement mesuré couche par couche, révèle que de nombreuses données d'épaisseur ont été calculées au nombre de pas. Se rendant compte que le stratotype qu'il avait mesuré était trop détaillé pour les revues scientifiques de l'époque, Logan avait publié ses travaux dans une publication gouvernementale relativement obscure où ils sont demeurés pratiquement inaperçus pendant près d'une décennie. John William Dawson et Charles Lyell, qui n'étaient pas au courant du stratotype mesuré par Logan, se sont rendus à Joggins en 1852 et ont mesuré le stratotype eux-mêmes. Dawson a ultérieurement laissé entendre que les deux stratotypes présentaient seulement des différences minimes, mais une comparaison attentive révèle que leurs descriptions et leurs mesures sont ra...
The Marquis of Salisbury’s 1894 address to the British Association for the Advancement of Science sparked an important development in the debate on the age of the Earth. It led John Perry, a physicist, to produce the first mathematical rebuttal of Lord Kelvin’s calculations, which had since 1862 functioned as an argument against the theory of evolution by natural selection. Perry wished to affirm the independence of geology from physics, keeping each branch of science to its proper domain. With the support of his mathematical friends, Perry tried privately to induce Kelvin to modify his views. This effort failed, however, and the discussion became public in Nature. Perry supported his calculations with Heaviside’s new mathematical methods, and also with empirical data, though these were later undermined by Kelvin’s experiments. Perry was uncomfortable with his position as Kelvin’s critic, however, because he held his old teacher in great esteem. Although Kelvin never stopped believing that the Earth was too young for natural selection to have taken place, geologists and biologists responded very positively to Perry’s results, and no longer felt they had to justify their conclusions to physicists. The answer to ‘Had Lord Kelvin a right?’, ultimately depended on one’s scientific politics.
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