Life's dawn on earth, the history of the oldest known fossil remains |
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Life's Dawn on Earth, the History of the Oldest Known Fossil Remains John William Dawson No preview available - 2013 |
Common terms and phrases
acervuline acid ancient animal appear beds Burgess calcareous calcareous matter calcareous skeleton calcite Canada Canadian canal system carbonate of lime Carpenter casts cavities cell-wall cells chambers character chemical chondrodite chrysotile corals creatures Crinoids crystals Dawson decalcified deposits Devonian dolomite Eozoic Eozoon Canadense evidence examined existence facts filled with serpentine Foraminifer Foraminifera formation forms fossils fragments geologists glauconite gneiss grains graphite Grenville Gümbel hornblende Hunt Huronian hydrous silicate infiltration intermediate skeleton King and Rowney laminated Laurentian limestones Laurentian rocks layers loganite Lower Laurentian Lower Silurian magnified malacolite mass metamorphic microscopic mineral minute structure modern Nummuline observed occur ocean ophite organic structure Paleozoic plates pores portions present preserved Primordial proper wall Protozoa pseudomorphous pyroxene resemblance sarcode sediments serpentine shells similar Sir W. E. Logan Sir William Logan slices species specimens of Eozoon sponges Stromatopora supplemental skeleton surface thickness tion traversed tubuli Tudor Upper Laurentian veins
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Page 45 - ... opened to those who will undertake the examination of rocks of various ages, which present the appearance of analogous structure ; as it is, the microscope has been the means of demonstrating the existence of animal life at a very ancient geological date ; and, in the words of Sir W. Logan, " we are carried back to a period so far remote that the appearance of the so-called Primordial Fauna may be considered a comparatively modern event.
Page 199 - Steatite, serpentine, pyroxene, hornblende, and in many cases, garnet, epidote, and other silicated minerals are formed by a crystallization and molecular rearrangement of silicates generated by chemical processes in waters at the earth's surface.
Page 79 - ... but communicating with each other by canals or septal orifices sparsely and irregularly distributed." He imagined, further, that the organisms grew in groups which ultimately coalesced and formed large masses penetrated by deep, irregular canals and that they continued to grow at the surface...
Page 52 - These masses of pyroxene may characterize a thickness of about 200 feet, and the interspaces among them are filled with a mixture of serpentine and carbonate of lime. In general a sheet of pure dark green serpentine invests each mass of pyroxene; the thickness of the serpentine, varying from the sixteenth of an inch to several inches, rarely exceeding half a foot. This is followed in different spots by parallel waving, irregularly alternating plates of carbonate of lime and serpentine, which become...
Page 29 - When it is considered that graphite occurs in similar abundance at several other horizons, in beds of limestone which have been ascertained by Sir WE Logan to have an...
Page 191 - ... the large scale, I would call attention to two admissions of the authors of the paper, which appear to me to be fatal to their case : First, they admit, at page 533 [Proceedings, vol. x], their "inability to explain satisfactorily" the alternating layers of carbonate of lime and other minerals in the typical specimens of Canadian Eozoon. They make a feeble attempt to establish an analogy between this and certain concentric concretionary layers; but the cases are clearly not parallel, and the...
Page 91 - I have not found in any of these fragments a canal system similar to that of Eozoon Canadense, though there are casts of large stolons, and, under a high power, the calcareous matter shows in many places the peculiar granular or cellular appearance which is one of the characters of the supplemental skeleton of that species. In a few places a tubulated cell-wall is preserved, with structure similar to that of Eozoon Canadense. " Specimens of Laurentian limestone from Wentworth, in the collection of...
Page 26 - But as wo do not as yet know with certainty either the base or the summit of this series, these three may be conformably followed by many more. Although the Lower and Upper Laurentian rocks spread over more than 200,000 square miles in Canada, only about 1500 square miles have yet been fully and Fig.
Page 171 - Laurentian and that of the Primordial Silurian or Cambrian period. It is scarcely too much to say that these inquiries open up a new world of thought and investigation, and hold out the hope of bringing us into the presence of the actual origin of organic life on our planet, though this may perhaps be found to have been Prelaurentian. I would here take the opportunity of stating that, in proposing the name Eozoon for the first fossil of the Laurentian, and in suggesting for the period the name
Page 171 - ... of certain low forms of plants and animals. Another is the comparison already instituted by Professor Huxley and Dr. Carpenter, between the conditions of the Laurentian and those of the deeper parts of the modern ocean. Another is the possible occurrence of other forms of animal life than Eozoon and Annelids, which I have stated in my paper of 1864, after extensive microscopic study of the Laurentian limestones, to be indicated by the occurrence of calcareous fragments, differing in structure...