Stephen K Donovan (The Netherlands)
The two most significant geologists to visit Jamaica and study its geology between the two World Wars were both British: Charles Alfred Matley (1866-1947) and Charles Taylor Trechmann (1885-1964). Both had active research programmes in Jamaica and the Antilles in the 1920s and 1930s, mainly on subjects that did not overlap, but the one geological concept on which they strongly disagreed was the one that underpinned all of their work – the geological evolution of the Caribbean basin.
C A Matley
Charles Matley (Fig. 1A) was a career civil servant and distinguished amateur geologist. He studied at the Birmingham and Midland Institute and the Mason Science College. The latter was incorporated into the new University of Birmingham in 1900. At Mason College, he was taught by Charles Lapworth, the father of the Ordovician System and one of the principal debunkers of Murchison’s assignment of the Scottish Highlands to the Silurian (Oldroyd, 1990). Matley’s principal field research while at Birmingham was on the Precambrian and Lower Palaeozoic of North Wales (for example, Matley, 1899, 1900, 1928), particularly Anglesey, work for which he was awarded a DSc by the University of London in 1902. Of particular relevance to his Jamaican research was his understanding of the geology of the Llyn Peninsula and Anglesey (McIlroy and Horák, 2006).
Matley’s later career took him further afield in the British Empire, including Ireland and India, where his researches examined topics as diverse as Carboniferous stratigraphy and dinosaur tracks (Donovan, 2010). He retired in 1920 and his experience in the Civil Service in Britain and overseas, and his wide geological experience, doubtless counted in his favour when he was appointed as geologist to the short-lived second geological survey of Jamaica (1922-1924). Later visits to the island came in 1938-1939 and 1943.
C T Trechmann
Charles Trechmann was an independently wealthy amateur geologist and archaeologist. He inherited an anhydrite mine from his father, the amateur mineralogist Dr Carl O Trechmann (1851-1917). Charles sold his inheritance to ICI in about 1924. He had already been awarded a DSc by the University of Durham for his research on the Zechstein (Permian) of northeast England and was now wealthy enough to pursue his geological interests wherever he chose – in northeast England during the summer and, commonly, the Antilles during the English winter (Donovan, 2003).
In the 1920s and 1930s, Trechmann would leave his home in County Durham once the winter set in and travel south to Southampton. He would then sail to the West Indies and would study some aspect(s) of the geology of one of the islands, which would result in a paper or papers that would later be published in Geological Magazine. Jamaica was a particular favourite and resulted in a number of papers on the Cretaceous and Cenozoic, particularly concerning the stratigraphy and fossil molluscs (such as Trechmann, 1923, 1929). The first stratigraphic column of the Jamaican succession had been published less than 25 years before Trechmann’s first paper on the island (Hill, 1899) and many aspects of the record were still poorly defined. Other Antillean islands on which Trechmann had a research interest included Antigua, Barbados, Carriacou, Trinidad and Tobago.
There seems to have been some early cooperation, or at least toleration, between Matley’s new geological survey and Trechmann, who was already an established expert on Jamaican geology. Initially at least, Trechmann agreed to concentrate on Jamaican palaeontology and the Cretaceous, while the survey worked on the Cenozoic. For example, much of the mapped area in Matley’s (1951) posthumous memoir of the Kingston district was part of the Cenozoic sedimentary succession. But it may be considered an error that Matley’s survey lacked a palaeontologist, although its remit was largely focussed on resources, including water (Donovan, 2010, p. 64). This merely repeated the error of the first geological survey (1859-1865), which did not replace the stratigrapher, Lucas Barrett, after his untimely death in 1862 (Chubb, 2010). In the 1920s, the only stratigrapher working in Jamaica was Trechmann, who was independent of the survey.
It was about this time that Trechmann began to extend his researches further afield in the English-speaking Caribbean. His Caribbean papers were all concerned with Jamaica between 1922 and 1924, but moved further afield thereafter, as indicated by his first papers on Barbados and Trinidad (Trechmann, 1925a, b). That Trechmann “… was unorthodox, a philanthropist and amusing, but could be antagonistic to his peers …” (Donovan, 2008, p. 607) is well known; it may be that geological ‘competition’ in Jamaica persuaded him elsewhere. However, he was working in Jamaica and publishing on the island’s geology again, soon after the demise of the survey. Yet, it was not until Matley (1929) published his full account of the Basal Complex that the (now defunct) second survey gave Trechmann a solid target with which to publicly disagree.
The Basal Complex
Matley’s first major publication to arise from his Jamaican research was the detailed account of the Basal Complex (Matley, 1929) and he recognised an unconformity at the base of the main Cretaceous-Cenozoic succession in Jamaica. The rocks below the unconformity were unfossiliferous and commonly crystalline, either metamorphosed or igneous intrusions. These rocks were the so-called Basal Complex, which Matley interpreted as remnants of a foundered Caribbean continent. The modern Antillean islands were considered to be built up on the peaks of this lost continent.
Publication in the Quarterly Journal of the Geological Society gave the theory a certain distinction, but, at most, its adherents were within Matley’s immediate circle. Significantly, Matley was an expert on the geology of North Wales and he impressed on Jamaica a structure reminiscent of the ‘Mona Complex’ of the Llyn Peninsula and Anglesey (McIlroy and Horák, 2006). This imposition of a geological structure from a well-known site to a new and distantly removed field area is called localism (Le Grand, 1988, pp. 80-81, 97; Donovan, 2013). Matley considered the rocks of the Basal Complex to be pre-Mesozoic or even Precambrian. Stratigraphic and radiometric evidence (Chubb and Burke, 1963) finally provided definitive proof that the age of the intrusions of the Basal Complex was latest Cretaceous to earliest Palaeocene. Therefore, Matley’s unconformity is, at best, only local – in many places it is a faulted contact or even conformable and there are no proven pre-Cretaceous rocks in Jamaica and there is no Antillean Basal Complex.
The few supporters of the Basal Complex did not include Trechmann and his field evidence suggested that the Basal Complex was intercalated with Cenozoic rocks. Trechmann did not accept Matley’s postulated great age for the complex, nor did he see any necessity for the islands to have an ancient continental basement. So Trechmann, who was not shy to state his position, took Matley to task in print.
Matley’s (1929) explanation of the Basal Complex in Jamaica was repeated and supplemented in later papers (such as Matley, 1936, 1937, 1951). As already mentioned above, there was little evidence to support his idea. The rocks of the so-called Basal Complex were metamorphosed and did not yield fossils; they were considered to be unconformable under the Upper Cretaceous; and the granodiorite was considered not to penetrate the Upper Cretaceous. In contrast, Trechmann (for example, 1936a, b, 1937) recognised no evidence for an old basement in Jamaica and considered that the granodiorite was intrusive, not just into the Upper Cretaceous, but also the Tertiary White Limestone (although the latter was erroneous, being based on complexly faulted contacts).
The theory of Mountain Uplift
Matley’s Basal Complex theory could not be dismissed out of hand because, at the time, there was no generally accepted explanation of island uplift and mountain building. Continental drift was receiving more positive attention in Europe than in North America, but was still far from widely accepted, and would not be so until the 1950s and 1960s (Oreskes, 1999; Powell, 2015). In fact, Trechmann’s comments on continental drift were dismissive (1955, pp. 58-60) and, if he disagreed with Matley over the Basal Complex, he needed to formulate his own consistent theory to explain the existence of the Antilles.
Trechmann’s position as an independently wealthy amateur geologist meant that, if his papers were not accepted for publication in mainline geological journals, he could afford to publish them himself. Consequently, the principal explanations of Trechmann’s Theory of Mountain Uplift were printed in a series of monographs that were privately published by the author (such as Trechmann, 1945, 1955). Otherwise, Trechmann’s theory was rarely mentioned in the scientific literature (see Trechmann, 1958, for an exception).
The explanation of the Theory of Mountain Uplift listed as seven points below is taken from Trechmann (1955, pp. 5-6):
Lunar and possibly solar attraction draws up the higher and more compact rock masses, allowing the lower parts to remain low or to become warped downwards as a reverse movement, the downward trend being increased by the weight of oceanic water.
Deep columns of oceanic water exert pressure on the floor or sloping sides of the submerged land and thus reinforce the upward pull.
Gravitation towards a submerged mass induces sediment to accumulate in the vicinity and this when consolidated can become drawn up as land on the flank of the older mass.
Cohesion or drawing together of a mass as it rises towards or above sea level tends to produce underthrusting and involvement of parts of the covering strata, and quite superficial material may be crushed and sheared in the process.
Resistance of water to pressure protects permeable strata from being crushed below sea level while old dry crystalline rocks that enclose such strata may be crushed. The same process if continued above sea level on land may crush and shear dry strata.
Chemical change such as crystallization, metamorphism or production of material like lava, induced by penetrating sea water, generates exothermic heat and causes conglomerates to become soft but sticky and allows the solid masses above to respond to the upward pull. Where magma has been generated below, a volcanic focus may erupt.
Downward sliding under gravity may cause slumping and contortion. The effect of the Moon in pulling up and pulling together may cause thrusting either horizontally or inclined. The two processes acting against each other may produce contortion of the strata.”
The principal target for Trechmann’s theory, Matley, died in 1946 and his posthumous monograph on the geology of the Kingston district was published in 1951. Trechmann exchanged offprints with Matley (Donovan, 2014), so at least the 1945 monograph would have been seen by him. However, after Matley’s death, the Basal Complex was forgotten by all but Trechmann. His Theory of Mountain Uplift had the support of no one in a scientific climate in which palaeomagnetism and marine geophysical research were laying the essential building blocks of the theory of plate tectonics. Trechmann died in Barbados in 1964, following an accident in the field.
|Modern ideas on Caribbean tectonics|
|For an introduction to modern ideas on the geological evolution of the Caribbean, Pindell (1994), although a little long in the tooth, remains a readable and well-illustrated account for the uninitiated. My account below is a simplification of a complex history. Matley would have been surprised to learn that there was no Caribbean Sea until the Jurassic and Trechmann would be unimpressed that it can all be explained by plate tectonics or, to him, continental drift.|
Rifting between North and South America began in the Middle Jurassic, about 170Ma, driven by a spreading centre between the two continents until about 100Ma (mid-Cretaceous). This spreading centre was probably related to the young Mid-Atlantic Ridge. By the mid-Cretaceous, a volcanic arc extended between North and South America in a position corresponding loosely to modern Central America, with the Caribbean crust being subducted beneath it. The plate on the ‘Pacific’ side of this arc, a thick basalt plateau, was now forced between North and South America. This formed the modern Caribbean Plate and the volcanic arc was ‘smeared’ along the north and south margins, and partly forms the modern Aves Ridge, mostly submerged and situated to the west of the modern Lesser Antilles volcanic arc. The modern Caribbean Plate is overriding the North and South American Plates to the east; is being deformed north and south, as it moves east as the adjacent American plates move west; and is overriding Pacific plates beneath Central America to the west.
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Trechmann, C.T. 1929. Fossils from the Blue Mountains of Jamaica. Geological Magazine, 66: 481-491.
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Trechmann, C.T. 1955. The British Association for the Suppression of Science or A New Explanation of Mountain Uplift, Based on Lunar Gravitation and Ocean Pressure. Privately published, Castle Eden, Co. Durham: 64 pp.
Trechmann, C.T. 1958. The evidence for cosmic upward pull in mountain and land uplift. Geological Magazine, 95: 426-436.
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