Pub Date : 2021-05-26DOI: 10.1017/S1755691021000037
D. Jolley, J. Millett, N. Schofield, L. Broadley, M. Hole
ABSTRACT The integration of biostratigraphical, wireline log, geophysical and available geochronological ages has identified two principal periods of volcanism in the Faroe–Shetland and Rockall basins. The first is pre-breakup, upper Danian to lower Thanetian: in the Rockall and Faroe–Shetland basins, isolated volcanic activity from 62 Ma to 58.7 Ma is identified in areas closely linked to the SSW–NNE structural fabric of the continental margin. Volcanic activity was concentrated at basin flank fissures and localised point sources. This rift-flank volcanism led to widespread volcanic ash deposition, localised lava flow fields and the formation of igneous centres. Some of the Hebridean and onshore central complexes (e.g., Rum) were uplifted and rapidly eroded during the later pre-breakup period, while additional accommodation space was developed in the adjacent offshore basins. Onset and termination of pre-breakup volcanism is correlated to intra-plate stress regimes in Europe, following the cessation of convergence of Africa and Europe in the Danian. The second is syn-breakup, upper Thanetian to Ypresian, initiated at ca.57 Ma in the Rockall and Faroe–Shetland basins. Initial high-volume extrusive igneous successions were focussed to the W in the Faroe–Shetland Basin. In the centre and E of the Faroe–Shetland and Rockall basins, separate eruption loci developed along pre-existing lineaments either as fissure or point-sourced lava fields. Short-term cessation of eruption at ~55.8 Ma was followed by resumption of flood basalt eruptions and a shift in focus to the NW. Fluctuations in the syn-breakup eruption tempo are reflected in the formation and subsequent rejuvenation of prominent unconformities, only previously recognised as a single erosive event. The W and northward shift of eruption focus, and the eruption of mid ocean ridge basalt-type lavas in the syn-breakup period reflect the onset of lithospheric thinning in the nascent North Atlantic Rift prior to flooding of the rift and eruption of the widespread lower Ypresian Balder Formation tephras.
{"title":"Stratigraphy of volcanic rock successions of the North Atlantic rifted margin: the offshore record of the Faroe–Shetland and Rockall basins","authors":"D. Jolley, J. Millett, N. Schofield, L. Broadley, M. Hole","doi":"10.1017/S1755691021000037","DOIUrl":"https://doi.org/10.1017/S1755691021000037","url":null,"abstract":"ABSTRACT The integration of biostratigraphical, wireline log, geophysical and available geochronological ages has identified two principal periods of volcanism in the Faroe–Shetland and Rockall basins. The first is pre-breakup, upper Danian to lower Thanetian: in the Rockall and Faroe–Shetland basins, isolated volcanic activity from 62 Ma to 58.7 Ma is identified in areas closely linked to the SSW–NNE structural fabric of the continental margin. Volcanic activity was concentrated at basin flank fissures and localised point sources. This rift-flank volcanism led to widespread volcanic ash deposition, localised lava flow fields and the formation of igneous centres. Some of the Hebridean and onshore central complexes (e.g., Rum) were uplifted and rapidly eroded during the later pre-breakup period, while additional accommodation space was developed in the adjacent offshore basins. Onset and termination of pre-breakup volcanism is correlated to intra-plate stress regimes in Europe, following the cessation of convergence of Africa and Europe in the Danian. The second is syn-breakup, upper Thanetian to Ypresian, initiated at ca.57 Ma in the Rockall and Faroe–Shetland basins. Initial high-volume extrusive igneous successions were focussed to the W in the Faroe–Shetland Basin. In the centre and E of the Faroe–Shetland and Rockall basins, separate eruption loci developed along pre-existing lineaments either as fissure or point-sourced lava fields. Short-term cessation of eruption at ~55.8 Ma was followed by resumption of flood basalt eruptions and a shift in focus to the NW. Fluctuations in the syn-breakup eruption tempo are reflected in the formation and subsequent rejuvenation of prominent unconformities, only previously recognised as a single erosive event. The W and northward shift of eruption focus, and the eruption of mid ocean ridge basalt-type lavas in the syn-breakup period reflect the onset of lithospheric thinning in the nascent North Atlantic Rift prior to flooding of the rift and eruption of the widespread lower Ypresian Balder Formation tephras.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"112 1","pages":"61 - 88"},"PeriodicalIF":1.2,"publicationDate":"2021-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S1755691021000037","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43521672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-24DOI: 10.1017/S1755691021000062
J. Woolf
James Croll (1821–1890) was a gifted scientist whose revolutionary theories had a profound impact on our understanding of the Earth's climate, ice ages and glaciation. While his contributions are recognised by an increasing number of modern-day scientists, in the public domain his legacy has been all but forgotten. Popularising Croll's story brings its own challenges: we know more about the science than we do about the man, and his theories do not lend themselves to quick and easy explanation. While Croll's scientific theories, presented alone, risk being viewed as complex and difficult to digest, his lifelong struggle against adversity is a compelling story with the potential for widespread public appeal. In recent years, interested individuals and institutions have begun to increase public awareness of Croll through talks and lectures, exhibitions, theatrical events and articles in print and online. There are many more possibilities that are worth investigating, in order to inspire and engage people locally, nationally and even internationally. Croll's story is fascinating from many points of view, and is open to interpretation by people of different ages and backgrounds. Perhaps even the gaps in our knowledge can be turned to advantage, allowing for imagination, creativity and expression.
{"title":"Popularising Croll: an opportunity for expression and creativity","authors":"J. Woolf","doi":"10.1017/S1755691021000062","DOIUrl":"https://doi.org/10.1017/S1755691021000062","url":null,"abstract":"\u0000 James Croll (1821–1890) was a gifted scientist whose revolutionary theories had a profound impact on our understanding of the Earth's climate, ice ages and glaciation. While his contributions are recognised by an increasing number of modern-day scientists, in the public domain his legacy has been all but forgotten. Popularising Croll's story brings its own challenges: we know more about the science than we do about the man, and his theories do not lend themselves to quick and easy explanation. While Croll's scientific theories, presented alone, risk being viewed as complex and difficult to digest, his lifelong struggle against adversity is a compelling story with the potential for widespread public appeal. In recent years, interested individuals and institutions have begun to increase public awareness of Croll through talks and lectures, exhibitions, theatrical events and articles in print and online. There are many more possibilities that are worth investigating, in order to inspire and engage people locally, nationally and even internationally. Croll's story is fascinating from many points of view, and is open to interpretation by people of different ages and backgrounds. Perhaps even the gaps in our knowledge can be turned to advantage, allowing for imagination, creativity and expression.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"1 1","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2021-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S1755691021000062","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47465100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-17DOI: 10.1017/S1755691021000104
M. Robinson
The quality and richness of Perthshire's natural environment were formative influences on a young James Croll (1821–1890), which left him with a life-long appreciation of nature, landscape and natural meditation. Although Croll himself declares to have had little interest in geology in his earlier years, it became a central theme of his scientific understanding, which implies the clear influence of both his local environment and of his father David, a stonemason. His family and friends also shaped him in other ways, not least his love of reading, his unconstrained thinking and intellectual acuity. He inherited his father's moral character, amiability and an excitement about intellectual inquiry, which drew friends to him who made great efforts to assist him in his work, both personally and professionally, and played a role in his being offered a position by James Geikie with the Geological Survey of Scotland. Croll's financial position was often precarious; he spent a good deal of his life in relative poverty. Whilst this affected his opportunities for formal learning, it may well have led to his ability to think creatively and to seek answers more broadly than he might have if he had been able to engage in a more formal education. Ill health, which affected him throughout his life, could be seen to both hamper his work – but also through circumstance lead him to pursue a more academic path, as other routes of work were shut off to him. Ultimately Whitefield, Wolfhill and the wider Perthshire countryside in which he grew up can clearly be seen to have influenced his life in many ways, even, perhaps, to the extent of his chosen surname.
{"title":"Dr James Croll: a product of his environment? An exploration of the natural, social, personal and economic factors that influenced his extraordinary life","authors":"M. Robinson","doi":"10.1017/S1755691021000104","DOIUrl":"https://doi.org/10.1017/S1755691021000104","url":null,"abstract":"\u0000 The quality and richness of Perthshire's natural environment were formative influences on a young James Croll (1821–1890), which left him with a life-long appreciation of nature, landscape and natural meditation. Although Croll himself declares to have had little interest in geology in his earlier years, it became a central theme of his scientific understanding, which implies the clear influence of both his local environment and of his father David, a stonemason. His family and friends also shaped him in other ways, not least his love of reading, his unconstrained thinking and intellectual acuity. He inherited his father's moral character, amiability and an excitement about intellectual inquiry, which drew friends to him who made great efforts to assist him in his work, both personally and professionally, and played a role in his being offered a position by James Geikie with the Geological Survey of Scotland. Croll's financial position was often precarious; he spent a good deal of his life in relative poverty. Whilst this affected his opportunities for formal learning, it may well have led to his ability to think creatively and to seek answers more broadly than he might have if he had been able to engage in a more formal education. Ill health, which affected him throughout his life, could be seen to both hamper his work – but also through circumstance lead him to pursue a more academic path, as other routes of work were shut off to him. Ultimately Whitefield, Wolfhill and the wider Perthshire countryside in which he grew up can clearly be seen to have influenced his life in many ways, even, perhaps, to the extent of his chosen surname.","PeriodicalId":55171,"journal":{"name":"Earth and Environmental Science Transactions of the Royal Society of Edinburgh","volume":"1 1","pages":"1-7"},"PeriodicalIF":1.2,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S1755691021000104","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41813599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-10DOI: 10.1017/S1755691021000190
Diarmid A. Finnegan
Science, for James Croll, began and ended in metaphysics. Metaphysics, in turn, provided proof of a First and Final Cause of all things. This proof rested on two metaphysical principles: that every event must have a cause, and that the determination of a cause is distinct from its production. This argument emerged from his deeply held religious commitments. As a 17-year-old, he converted to a Calvinist and evangelical form of Christianity. After a period of questioning the Calvinist system, he embraced it again through reading the famous treatise on the will by the New England theologian, Jonathan Edwards. This determinedly metaphysical work, which engaged as much with Enlightenment thought as with Calvinism, defended the view that the will was not a self-determining cause of human action. This ‘hard case’ provided the basis for a larger claim that every act whatever has a cause, and that the production of an act was different from its determination. In part through reading Edwards, Croll remained a devout and convinced ‘moderate’ Calvinist for the rest of his life. He also developed a deep love of metaphysics and became convinced that without it, everything, including science, remained confused and in darkness. For Croll, even the most basic science could not be properly conducted without prior metaphysical principles. But this was more than just an argument about the philosophical foundations of scientific inquiry. It was also based on Croll's conviction that the cosmos, earth history and life (including his own) was fully determined by a supreme and perfect intellect. This conviction entered into the marrow of Croll's scientific theories and shaped his interpretation of the twists and turns of his own life. In short, to take seriously Croll's own self-understanding, we need to allow him to ‘do God’.
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Pub Date : 2021-05-10DOI: 10.1017/S1755691021000141
Laura Brassington
Scientific societies played a crucial role in the emergence of a professional culture of science in Britain in the midto late-19th Century. At first sight, James Croll’s membership of a limited numberof scientific associations may be assumed to be the result of his lackof social credit and scientific connections. In this article, by examining Croll’s correspondence, I demonstrate that Croll’s select participation in scientific clubs and associations reflected his strategic pursuit of a vision of science set apart from party or societal affiliation. I focus on the contrasting histories of the Royal Society of Edinburgh and the Geological Survey, as well as the institutional history of the Philosophical Magazine. Situating the institutions in their respective social and cultural contexts, I argue that the more meritocratic, inclusive social structure of the Survey and Magazine helps explain Croll’s choice to avoid affiliation with the Royal Society of Edinburgh.
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Pub Date : 2021-05-10DOI: 10.1017/S1755691021000116
J. Rose
Within the context of the work and achievements of James Croll, this paper reviews the records of direct observations of glacial landforms and sediments made by Charles Lyell, Archibald and James Geikie and James Croll himself, in order to evaluate their contributions to the sciences of glacial geology and Quaternary environmental change. The paper outlines the social and physical environment of Croll's youth and contrasts this with the status and experiences of Lyell and the Geikies. It also outlines the character and role of the ‘Glasgow School’ of geologists, who stimulated Croll's interest into the causes of climate change and directed his focus to the glacial and ‘interglacial’ deposits of central Scotland. Contributions are outlined in chronological order, drawing attention to: (i) Lyell's high-quality observations and interpretations of glacial features in Glen Clova and Strathmore and his subsequent rejection of the glacial theory in favour of processes attributed to floating icebergs; (ii) the significant impact of Archibald Geikie's 1863 paper on the ‘glacial drift of Scotland’, which firmly established the land-ice theory; (iii) the fact that, despite James Croll's inherent dislike of geology and fieldwork, he provided high-quality descriptions and interpretations of the landforms and sediments of central Scotland in order to test his theory of climate change; and (iv) the great communication skills of James Geikie, enhanced by contacts and evidence from around the world. It is concluded that whilst direct observations of glacial landforms and sediments were critical to the long-term development of the study of glaciation, the acceptance of this theory was dependent also upon the skills, personality and status of the Geikies and Croll, who developed and promoted the concepts. Sadly, the subsequent rejection of the land-ice concept by Lyell resulted in the same factors challenging the acceptance of the glacial theory.
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Pub Date : 2021-05-10DOI: 10.1017/S1755691021000050
J. Croll, D. Sugden
At a time when nobody has yet landed on the Antarctic continent (1879), this presentation and accompanying paper predicts the morphology, dynamics and thermal regime of the Antarctic ice sheet. Mathematical modelling of the ice sheet is based on the assumptions that the thickness of tabular icebergs reflects the average thickness of the ice at the margin and that the surface gradients are comparable to those of reconstructed former ice sheets in the Northern Hemisphere. The modelling shows that (a) ice is thickest near the centre at the South Pole and thins towards the margin; (b) the thickness at the pole is independent of the amount of snowfall at that place; and (c) the mean velocity at the margin, assuming a mean annual snowfall of two inches per year, is 400–500 feet per year. The thermal regime of the ice sheet is influenced by three heat sources – namely, the bed, the internal friction of ice flow and the atmosphere. The latter is the most significant and, since ice has a downwards as well as horizontal motion, this carries cold ice down into the ice sheet. Since the temperature at which ice melts is lowered by pressure at a rate of 0.0137 °F for every atmosphere of pressure (something known since 1784), much of the ice sheet and its base must be below the freezing point. Estimates of the thickness of ice at the centre depend closely on the surface gradients assumed and range between 3 and 24 miles. Such uncertainty is of concern since both the volume and gravitational attraction of the ice mass have an effect on global sea level. In order to improve our estimate of the volume of ice, we will have to wait 76 years for John Glen to develop a realistic flow law for ice.
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Pub Date : 2021-05-10DOI: 10.1017/S1755691021000165
M. Longair
James Croll was a pioneer in studies of the impact of the slowly changing orbital dynamics of the Earth on climate change. His book Climate and Time in their Geological Relations (1875) was far ahead of its time in seeking correlations between climate change, the occurrence of ice ages and perturbations to the Earth’s orbit about the Sun. The astronomical cycles he discovered are now called ‘Milankovitch Cycles’ after the Serbian scientist whose research was first published in the Handbuch der Klimatologie in 1930. The celestial mechanical and astronomical background to Croll’s research is the focus of this essay. The development of the understanding of the impact of perturbations of the elliptical planetary orbits by other bodies in the solar system paralleled new mathematical techniques, many of which were developed in association with celestial mechanical problems. The central contributions of many of the major mathematicians of the late 18th and 19th Centuries, including Euler, Lagrange, Laplace and Le Verrier, are highlighted. Although Croll’s contributions faded from view for several generations, his pioneering insights have now been demonstrated to have been basically correct.
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Pub Date : 2021-05-10DOI: 10.1017/S1755691021000177
P. Tzedakis, E. Wolff
James Croll's Physical Theory of Secular Changes of Climate emerged during an age of revolution in geology that included the rise of the glacial theory and the search for its underlying causes. According to Croll, periods of high eccentricity are associated with the persistence of long glacial epochs, within which glaciations occur in alternate hemispheres when winter is at aphelion every ~11,000 years; however, astronomical forcing is only able to produce glaciation by means of physical agencies (climate feedbacks) that amplify the small effects of varying seasonal irradiation. Croll understood the importance of interglacial deposits because they provided evidence for the occurrence of multiple glaciations within his long glacial epochs. He was aware of the limitations of the terrestrial record and suggested that deep-sea sediments would contain a continuous succession of glacial-interglacial cycles. Contrary to a widespread view, however, Croll was not envisaging the advent of palaeoceanographic exploration avant la lettre, but instead was drawing attention to the inadequacy of the land record as a testbed of his astronomical theory. Yet, the marine record did eventually deliver a test of astronomical theories almost exactly 100 years after the publication of his 1875 book Climate and Time in their Geological Relations. Here, we provide an historical account of the technological and scientific developments that led to this and a summary of insights on astronomically paced climate changes from marine, terrestrial and ice core records. We finally assess Croll's ideas in the context of our current understanding of the theory of ice ages.
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Pub Date : 2021-05-10DOI: 10.1017/S1755691021000098
J. Fleming
This paper examines the astronomical theory of ice ages of James Croll (1821–1890), its influence on contemporaries John Tyndall, Charles Lyell, and Charles Darwin, and the subsequent development of climate change science, giving special attention to the work of Svante Arrhenius, Nils Ekholm, and G. S. Callendar (for the carbon dioxide theory), and Milutin Milanković (for the astronomical theory). Croll's insight that the orbital elements triggered feedbacks leading to complex changes – in seasonality, ocean currents, ice sheets, radiative forcing, plant and animal life, and climate in general – placed his theory of the Glacial Epoch at the nexus of astronomy, terrestrial physics, and geology. He referred to climate change as the most important problem in terrestrial physics, and the one which will ultimately prove the most far reaching in its consequences. He was an autodidact deeply involved in philosophy and an early proponent of what came to be called ‘cosmic physics’ – later known as ‘Earth-system science.’ Croll opened up new dimensions of the ‘climate controversy’ that continue today in the interplay of geological and human influences on climate.
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