CHAPTER 1 - GENERAL REVIEW
1.A Introduction
An early achievement of geological science was the recognitionthat certain areas underlain by deformed and metamorphosed rocks are the ancient, eroded analogues of present day mountain systems.One such area is Newfoundland, which forms the northern extremity of the Appalachians. If one allows the validity of Uniformatarianism,the forces that made modern mountains also moulded the Appalachians.
A major problem in writing this thesis has been the remarkable and rapid changes in our understanding of the origin of modern mountainsduring the writer's attempts to commit pen to paper. Studies in Newfoundland during this time have played no small part in the application of modern plate tectonic theory to ancient mountain systems.
This thesis will attempt to show how our present views on the development of the western part of the Appalachians in Newfoundlandhave evolved since the first investigations and will try to delineate some of the major problems now faced by geologists who wish to understand how plate tectonics can be applied to the Appalachians. Because of the rush of new ideas and new data and a growing awarenessof the complexity of the problem, this attempt must leave many loose ends.
The writer started work on the problems of west Newfoundland geology in 1963 under the guidance of H.D. Lilly at the MemorialUniversity of Newfoundland. Between 1965 and 1967 he worked in the area for the Geological Survey of Canada. From 1967 to 1970 he worked with W.R. Church at the University of Western Ontario. A short, but interesting time at the University of Toronto as research associate to J.T. Wilson has been followed by research and teaching at the Memorial University of Newfoundland.

1-B Investigations up to 1971
The geological importance of Newfoundland was first clearly under-stood by Sir William Logan who recognized that the excellent shore exposures of the island could provide answers to many of the problems not easily solved in the less well exposed Appalachians of the Canadian Mainland. Logan was so intrigued by the potential of Newfoundland to solve problems of Canadian geology that he sent Richardson to work in west Newfoundland even though Newfoundland was not part of the CanadianConfederation at that time. Newfoundland's first geological links werewith the Appalachians.
The links to the Caledonian system of north west Europe andGreenland were recognized much later (Wegener.1924; Bailey. 1927, 1929) but not until the Gander Conference in 1967 (Kay. 1969) was it generallyaccepted that the Appalachians and the Caledonides are, in fact, partof the same orogen. Newfoundland and Ireland were once much closer together but are now separated by the Atlantic Ocean. The orogenic system is common to North America and Europe and this is of some importance to the history of geology since it has provided a common testing ground for ideas generated in two separate schools of geological thought.
The early history of geological investigation in Newfoundland has recently been reviewed by Baird (1975) and involves such illustrious names as Captain James Cook and Sir Joseph Banks. The basic geological framework, however, was laid by James Richardson during summers of 1857 to 1863. His results were first published by Billings in 1862 but appeared in detail in the "Geology of Canada" (Logan, 1863). Richardson worked almost entirely in west Newfoundland where he constructed a strati graphic section that has remained the basis of all subsequent investigations (Table I). As a result of Richardson's work in west Newfoundland, Logan was able to correlate these rocks with the Quebec and Taconic Groups and conceived his idea that not only was much of the Quebec Group in Quebec and Newfoundland allochthonous, but, prior to its transportation, it formed part of an ancient con- tinental margin (Stevens, 1974). This aspect of Logan's work is treated more fully later in this thesis.
 Following the publication of the "Geology of Canada", the Newfoundland government started a geological survey of its own in an attempt to develop the economy of the island. Alexander Murray, previously Logan's assistant in Quebec and Ontario, was hired in 1864 to direct the Survey. A short biography of Murray is given by Bell (1892). In 1869, James P. Howtey became Murray's assistant and eventually succeeded Murray when he retired in 1883. Howtey retired in 1909.
 The results of the Survey are contained in annual reports to the Newfoundland government which were compiled and published in book form in 1881 and 1918. Murray compiled the first geological map of the island in 1873. It was reissued in 1877. Howley published a map in 1909 with reprintings in 1915 and 1925.
 Murray and Howley studied most of the coastal and river sections in west Newfoundland and described them using Richardson's stratigraphic nomenclature. Much of their work concerned the potentially  economic rocks of Carboniferous age but also delineated the distribution of older rocks which they referred to the Cambrian and Silurian systems. (It is hard to understand Shuchert and Dunbar's [1934, p.3] criticism of Murray's assignation of Ordovician rocks as Silurian since at the time Murray started work there was no Ordovician system. Murray was merely using stratigraphic nomenclature used at the time by the Geological Survey of the United Kingdom.)
 The relevant parts of Murray and Howley's reports are those for 1864, 1865, 1866, and 1877. A brief review of the early Newfoundland Survey publications can be found in Nature (A.G., 1876). Even at this early date the significance of geological investigation in Newfoundland for the interpretation of the geology of Scotland appears therefore to have been recognized.
 Although Murray and Howley's work did not lead to any basic change in the understanding of the geology of west Newfoundland it did stimu- late several private economic surveys. Most of the reports of these surveys are in the Newfoundland Government files and are listed in Betts (1936) and Butter and Barttett (1969).
 During the early part of the present century, Yale and Princeton universities established field programs in Newfoundland. The main concern of the Yale group, directed by C. Schuchert, was the sedimentary sequences of west Newfoundland. The Princeton group, directed by G. van Ingen, concentrated in Notre Dame Bay and, later, northern Newfoundland and the Bay of the Islands area.
 The results of the Yale program are contained in Schuchert and Dunbar's (1934) "The Stratigraphy of Western Newfoundland", though several theses were submitted after this date (Sullivan, 1940; Troelsen, 1947; Smith, 1952; and Weitz. 1953).
 The stratigraphic sequence established by Schuchert and Dunbar is reproduced in Table I. According to Schuchert and Dunbar (1934), the Lower Cambrian Labrador Group unconformably overlies Laurentian Gneiss. No Middle Cambrian rocks are present. The Upper Cambrian is represented by the March Point Formation which marks the onset of shallow water carbonate sedimentation that continues from the Canadian (St. George Formation) to the Chazy (Table Head) and the Black River (Long Point).
 The lowest Canadian Green Point Series of graptotite-bearing shales and thinly bedded limestones presented difficulties of inter- pretation since they very much resembled the presumed much younger Humber Arm Series. Schuchert and Dunbar (1934, p. 40) suggested that the Green Point Series was either older than the St. George or a near shore fades of the St. George. They preferred the former interpretation. A spectacular sequence of limestone breccias above the Table Head was taken to have formed during Middle Ordovician thrusting since in at least one locality the breccias are interbedded with Middle Ordovician graptotite-bearing shales. The faulting was thought to be related to uplift in the east that gave rise to the thick clastic sequence of the Humber Arm Series of Mid and perhaps Late Ordovician age. No diagnostic fossils were reported from the Series except from close to its contact with the Table Head.

  				Historical Geology of Newfoundland

 Western             (Northern)      Interior         Southeastern.
 Pleistocene -  GIacation and crustal oscillation.
 Pliocene to Eocene -  No sedimentary record.Peneplane of summit of Long Range uplifted and partially destroyed by long erosion, reducing the Gulf of St. Lawrence area to a lowland later submerged by crustal warping.
 Jurassic/Cretaceous - No sedimentary record known. Newfoundland probably subjected to continued erosion.
 Permian_______ Folding and faulting during Appalachian revolution followed by long erosion interval.__________
 Land interval
 Pennsylvanian       ?L^ g^, Measures. all continemta;        ,                  ,          Erosion interral
 ____________ Land interval
 Windsor series of
 ,„ . . .         __ ,                                              Humber River, Windsor dif'
 Mississippian       Windsor series S450'               No record known    Deer and Grand  turbaw
 lakes, and Bad In- Erosion ioterrai
 .____________ ______________________ ____________ dian Lake_____ ___--_________
 _ Land interval                  Acadian dittw^ww    Acadian disturbance
 Acadian dzstmbsnw sad bwe    and basic intrusions-   and basic intrusions Acadian du<)'^aie»
 Devonian          __ intrusions___________ eons________ eons________ _____________
 ^ Clam Bank •erie
 1700'       No record known   No record known   Erosion interval
 Silurian in White                   Silurian orogeny
 Silurian            No record known                  No^r^'4? ^d No record known    ably deposited. Now
 _______________________________(20W)        y____________eroded away
 _____d»vs^_    disturbance         disturbance          di^^nn     Taconusn ditturbww
 Humber   Arm Present in Pistolet          ,
 5         Q     aerial at least   Bay in far N. Also „,   . '
 ^ -.   much    5000'            in Notre Dame Volcanics
 _,      extended Highland
 rising Bay with B«d Cliff shales wlth 8"?"
 g __ _____  toeaat_____ volcanics______ tollte'
 s              Cow Head thrust ••- «
-     v           breccia                            -,      , ,
 "5               Faulting •ml <•)«.                     No record known   . „         ,
 ^                vation          GOM Pond volcao-   -                 An y°«W,to™»
 Ordovician          -3 ^: ——0— ————5————— ica                ,., ,   .——————  tions eroded away
 SS? much  ^"S Ft- ""w                   ^y01?"",
 __ a= exTend^ l5sot         ____________ ^^bly repre-
 1  &•    N    ^ ».. ,T .   .   Snooks Arm vol- Table Head present'
 ff S     to     Table Head acnes camcs              as  shales with
 -; Q     K     ls80'          Table Head prewat  graptolitw
 ^__________________as shales______^)lcanics____________
 5       I     St. George series Later St George  Late St. George Wabana 3000'
 -5      n     1570'-3080'+     present a slates  present with grap- BeU I. 6000'
 g    ——u——________'      with volcanic-       tolites Volcanica  Clarenville_____
 ,=    . Q    Green Pt. series Probably repre- T;~—————~—~——————
 ___________'"'    in port   1700'-f-          3r-'ted             No record known    Possibly represented
 d             March Pt. series                  '''~~~ ~~'~~——————"
 ^   _____  1180'T-                ?                 p         Johanman 400'-500'
 C^ri.n            1_____Land interval               ;                         Manud, 300'
 6      »     Labrador series         ,                           ~r~~.~~~
 .S       »      2600'                  ?                 ?         Hanfordian
 ___________   '~'       A___________ ____________                    Etcheminian 200'
 Proterozoic          Great unconformity                Great unconformity ~——~——-————————-————————-
 ____________Record unknown____________Record unknown    Record unknown   Avalon series 15,000'
 Archeozoic           PLaureutian )?ranite                 ~''— Tu,,^nni-;^» ^. „•«.— "T————-—————-——•
 -———-—————————————————-—————————————____________I
 Laurentian  granite                                                                                I Laurentian granite
  
The entire Cambro-Ordovician sequence, broken only by disconformities in Middle Cambrian time and at the base of the Table Head, was thought to have been deformed at the end of the Ordovician during the Taconic orogeny and to be unconformably overlain by the Clam Bank Series of red beds of Lower Devonian age. The Acadian orogeny, accompanied by the intrusion of the ultramafic and mafic Bay of Islands Complex, further deformed the rocks of west Newfoundland which were then eroded and covered by Mississippian and Pennsylvanian sediments de- formed during the Appalachian revolution (Permian age). This geological framework served, with a few exceptions, as a standard frame of re- ference for all workers until 1963.
 Meanwhile, the Princeton geologists Ingerson (1935, 1937), Cooper (1936) and Buddington and Hess (1937) studied the Bay of Is- lands Igneous Complex. Ingerson, working in the northern part of the Complex, concluded that he was examining layered laccoliths of ultra- mafic and mafic rocks, most probably of Lower Devonian age. Buddington and Hess, working in essentially the same area felt that the intrusions were lopotiths. Furthermore, they thought that Table Mountain and North Arm Mountain formed parts of a single lopolith disrupted by westwards thrusting. Cooper (1936) reached a similar conclusion white working in the southern part of the complex. He suggested that the Blow me Down and the Lewis Hi 11s massifs were part of a great disrupted lopolith with a thickness of about 7 miles. He suggested that the floor of the lopolith consisted of schists derived from the Humber Arm sedi- ments and recognized that the roof consisted of volcanic and sedimentary rocks. Cooper (1936. p. 8) considered that the southern part of the Complex consisted of a gravity differentiated body with primary rhythmic banding and a secondary, parallel tectonic banding. Furthermore, Cooper recognized that the Bay of Islands Complex was related to the Mount Albert Complex of the Gaspe Peninsula of Quebec.8 All workers agreed that the igneous rocks intruded the Humber Arm Series.
 Cooper (1937) extended his work to the Hare Bay region of New- foundland under the auspices of the Newfoundland government. Table II shows his stratigraphic column and correlations. The most striking feature of the Hare Bay area recorded by Cooper is the spectactular thrusts that bring the Hare Bay uttramafic rocks and the Goose Cove Schists over the little metamorphosed Maiden Point and Goose Tickle sediments. Cooper (1937, p. 11) compared the thrusts with the Moine thrust of northwest Scotland. He correlated the uttramafic rocks above the thrust with the Bay of Islands Igneous Complex white the clastic rocks below were thought to be in place and equivalent to the Humber Arm Series of Middle Ordovician and later age.
 Betz (1939), also working from Princeton, described the geology of the Canada Bay area, south of Hare Bay, in terms of Schuchert and Dunbar's standard section. His stratigraphic column and correlation are reproduced in Table III.
 Between 1949 and 1955 several students from Columbia University, mainly directed by Marshall Kay, worked in west Newfoundland. These included walthier (1949). Oxtey (1953), and Nelson (1955). Of particular note is Walthier's suggestion that the metamorphic rocks east of Corner Brook are thrust over the carbonate rocks of the St. George Group. This suggestion, yet to be reconfirmed in the field, implies the existence of a Moine thrust-like feature in west New- foundland.

 Western Newfoundland             	Hare Bay
  							7. Ireland Point Volcanics
 2,000'
 Humber Arm      			 	6. Maiden Point sandstone
 Series              				6'000’
 5,000’				       		5. Goose Tickle Slate
 2,000'-5,000'

 Cow Head
 Breccia         				4. Northwest Arm Formation
 0-500'

 Long Point
 Series
 1,530'
 
 Table Head      				3. Hare Island Limestone
 Series—1,380'        			1,000'
 
 St. George      				2. Southern Arm Limestone
 Series              				1,500'+/-
 1,570'-2,080'
 
 Green Point     				1. Brent Island Limestone
 Series                 				350'+/-
 1,700’
 
 Table II. Stratigraphic Column and Correlations used by Cooper, 1937.
 
        Age                  		Betz (1939)
 Lower Middle               		Bide Arm Fm.
 Ordovician
 Middle Cambrian to         	Chimney Arm Fm.
 Early Ordovician
 Middle Cambrian            	Treytown Pond Fm.
 Early Middle               		Cloud Rapids Fm.
 Cambrian                   		
 Lower Cambrian            	Forteau Fm.
 Lower Cambrian             	Devils Cove Fm.
 Table III. Stratigraphic Column used by Betz, 1939.

The work of the American universities in western Newfoundland 'broadly confirmed and considerably refined the earlier results of the Canadian and Newfoundland Surveys. Logan's broad stratigraphic synthesis was polished, expanded and placed on a more secure basis.
 However, one curious and apparently minor difference of interpretation occurs in the descriptions of the Bonne Bay area given by Logan and a footnote in Schuchert and Dunbar.
 Logan (1863, p. 293) insisted that certain rocks, later included by Schuchert and Dunbar in their Humber Arm Series, were the equivalents of the Sillery and Levis Formations of his Quebec Group in Quebec. Logan's view was based mainly on lithic similarity and apparent stratigraphic position. Schuchert and Dunbar disagree (1934, p.95 ) in this correlation, however, and Logan appears to be wrong, since the greenish sandstones of Bonne Bay are not of Lower Ordovician age but are now known to be younger than the Long Point (=B1ack River) time.
 The key to much of the present interpretation of the geology of west Newfoundland is hidden within this apparently minor difference of opinion. To appreciate its significance, it is necessary to review briefly the early history of the Taconic problem in west Newfoundland, Quebec and New England. More detail can be found in Stevens (1974) and Zastow (1975).
 Early workers in the New England states and Quebec recognized three major rock sequences. The oldest rocks, gneisses and granites, formed the basement and the western foreland of the Appalachian system. These were referred to as the Laurentian System. The overlying rocks, sandstones, shales and carbonates of Cambrian and Lower Silurian (Ordovician) age, were subdivided into the Potsdam Group, the Calciferous, Chazy, Trenton, Hudson River, and Utica Formations. The third sequence of rocks, the Quebec and the probably correlative Taconic Groups, consisted mainly of clastic rocks. These were virtually without fossils and of intransigent aspect. They "looked" older than the second group and this was indeed Logan's first hypothesis (Logan, 1863, p. vii). Later field work demonstrated that in fact the Quebec Group rested on the fossiliferous Hudson River Formation. Logan assumed this was a normal sedimentary succession. Fossils were discovered in the Quebec Group and by 1860 '-' paleon- totogical evidence enabled Billings to state that the Quebec Group fossils were older than the Utica and about the same age as the under- lying Calciferous and Chazy Formations. Logan's first reaction was to believe the field data and to suggest that colonies (in the sense of Barrande) of older fossils had survived into post Utica times (Logan, 1860, in a letter to Barrande, quoted in Logan, 1863, p. viii). In the same year, after more fossils had been collected, Logan realized that the doctrine of colonies could not explain the exclusively primordal aspect of the fauna. He was forced to conclude that parts, at least, of the Quebec Group were time equivalents of the Calciferous and Chazy Formations. Now the problem was how could the Quebec Group overlie its time equivalents? Logan concluded that the Quebec Group must have been transported. He suggested that a great dislocation at the base of the Quebec Group brought it over the Utica Formation. Logan explained the lithological differences between the two sequences by suggesting that the autochthonous sequence was a shallow water shelf sequence whereas the Quebec Group formed in deep water at a continental margin. The ocean was named the Paleo Atlantic (Stevens, 1974, Fig. 3 ). It is not clear if this name was ever used by Logan or if it was coined by Dawson (VD_ Harrington, 1883).
 Logan, on the basis of Richardson's observations, recognized that the "Great Dislocation" should pass through the Bonne Bay area of west Newfoundland between his divisions N and Q. Logan, in other words, recognized that the Humber Arm Supergroup was transported. Schuchert and Dunbar rejected Logan's correlation and it was a hundred years before Logan's hypothesis was fully substantiated.
 Schuchert and Dunbar's failure is difficult to understand since, in the Taconic region, Ruedemam (1909) and Keith (1913) recognized that the Hudson River Group was thrust into its present position.
 This hypothesis was neither fully accepted or conclusively proven until quite recently (Zen, 1961), and several rival hypotheses existed (Zen, 1967). It is possible, therefore, that Schuchert, who started work in Newfoundland in 1910, did not accept the Taconic Klippe. However, Schuchert (1930, p. 711) shows that he understood the regional significance of Ruedemann's work and its relationship to Logan's work. He appreciated that Logan's Line "may be traced from Kingston, New York, and Lake Champlain to Quebec City, and thence it follows the estuary of the St. Lawrence, undoubtedly continuing to the south of Anticosti." (Schuchert, 1930. p. 711). Furthermore Schuchert realized that the thrusting took place within.the Ordovician Period (Schuchert, 1930, p. 718). Unfortunately, the faunal data on which Johnson's hypothesis rested has never been published, though lists of Johnson's graptolites appear in Ruedemann (1947, p. 59-60). Perhaps, for this reason, Johnson's conclusions did not become widely known or appreciated. Kay (1945, p. 442), however, accepted Johnson's hypothesis, but only for those rocks separated by Johnson from the Humber Arm. As late as 1951, Kay (1951, p. 52) cites west Newfoundland as an area where eugeosynclinal rocks follow on top of miogeosynclinal deposits. He regarded the igneous rocks as in situ intrusions. 
A major reinterpretation of the Humber Arm Supergroup had to await a reinterpretation of the Taconic region. Zen (1961) found that in west-central Vermont the Taconic allochthon definitely existed and that  its base was not the carbonate/shale contact but was well within the shale sequence. A description of the whole Taconic region can be found in Zen (1967) and a regional discussion in Zen (1972). 
In Newfoundland, yet another anomalous sequence of rocks had been discovered by Kindle and Whittington (1958, 1959). The Cow Head Breccias (Schuchert and Dunbar, 1934, p. 73) were not, at the type section, a chaotic thrust breccia but an orderly sequence of shales.
In Newfoundland, Schuchert and Dunbar (1934) and Dunbar (1934) recognized the importance of Middle Ordovician thrust faulting and found an anomalous sequence of rocks, the Green Point Series, indistinguishable from the Humber Arm Series (Schuchert and Dunbar, 1934, p. 38). Even with their wide knowledge of Appalachian geology, and the field evidence (the thrusts are clearly visible at several localities), Schuchert and Dunbar failed to make the logical deduction that the Humber Arm Series was, in large part, transported. Indeed. Schuchert (1930, p. 712) says "... the Quebec Group . . . (is) known in situ only in western Vermont and northern Newfoundland.". Perhaps part of the failure is explained by the scarcity of fossils in the Humber Arm. The fossiliferous Cow Head Breccias were misinterpreted as tectonic breccias and the fossiliferous Green Point Series was assigned an autochthonous position beneath the St. George even though it is never seen in this position.
 Perhaps of even greater importance is the marked fades convergence between the transported Humber Arm and the top of the autochthonous sequence. This is explained in a later section and it is sufficient to note here that the richly fossiliferous rocks above the Lower Table Head greatly resemble those of the Humber Arm, and it would seem logical, therefore, to assign a Middle Ordovician or later date to the Series.
 In 1941, however, H. Johnson, who had been working for the New- foundland government, recognized that the anomalous Green Point Series was only the oldest member of a thick sequence of shales, sandstones, carbonates and carbonate breccias, coeval with the St. George and Table Head Formations, that is of Tremadoc to Llanvirn age. Johnson (1941) separated the anomalous rocks from the unfossiliferous main bulk of the Humber Arm. He erected three new groups, the St. Pauls Group, the Western Brook Pond Group, and the Green Point Group. Johnson realized that his three new groups could not be fitted into Schuchert and Dunbar's (15 -> 16)standard scheme, so he suggested that these rocks had been thrust from a source in the east, over the Long Range crystalline rocks. The suggestion seemed reasonable, especially since Johnson (1941) found that the Long Range itself had been thrust to the west along horizontal thrusts. Johnson thought that the age of the thrusting was Taconic or Caledonian but stilt regarded the bulk of the Humber Arm to be in place. 
Unfortunately, the faunal data on which Johnson's hypothesis rested has never been published, though lists of Johnson's graptolites appear in Ruedemann (1947, p. 59-60). Perhaps, for this reason, Johnson's conclusions did not become widely known or appreciated. Kay (1945, p. 442), however, accepted Johnson's hypothesis, but only for those rocks separated by Johnson from the Humber Arm. As late as 1951, Kay (1951, p. 52) cites west Newfoundland as an area where eugeosynclinal rocks follow on top of miogeosynclinal deposits. He regarded the igneous rocks as in situ intrusions. 
A major reinterpretation of the Humber Arm Supergroup had to await a reinterpretation of the Taconic region. Zen (1961) found that in west-central Vermont the Taconic allochthon definitely existed and that  its base was not the carbonate/shale contact but was well within the shale sequence. A description of the whole Taconic region can be found in Zen (1967) and a regional discussion in Zen (1972). 
In Newfoundland, yet another anomalous sequence of rocks had been discovered by Kindle and Whittington (1958, 1959). The Cow Head Breccias (Schuchert and Dunbar, 1934, p. 73) were not, at the type'         . section, a chaotic thrust breccia but an orderly sequence of shales,   limestones and limestone breccias of Middle Cambrian to Middle Or- dovician age. The age of the dasts within any breccia bed is the same, as far as can be told, as the age of the interbedded black shale. Kindle and Whittington (1958, p. 341) suggested that the Cow Head Breccias are a type of flysch. They emphasized that there was no known source for many of the fossiliferous boulders since the equivalent carbonates of the shelf sequence are in large part very poorly fossiliferous.
Using the new information from the Taconics and west Newfoundland, Rodgers and Neate (1963) reinterpreted the Humber Arm Group as two large klippen, thereby bringing to fruition Logan's original concept. They drew a detailed strati graphic and structural analogy between the two Newfoundland ktippen and the Taconic Klippe and suggested that the New- foundland klippen were emplaced by gravity sliding from a source to the east of the Long Range. These authors were the first to include the igneous rocks of the Bay of Islands and Hare Bay in the trans- ported rocks, though they still assumed that these intruded the sediments of the Humber Arm, a relationship apparently confirmed by the detailed mapping of Smith (1958).
The age of sliding was deduced as Middle Ordovician, since the youngest rocks on which the klippen rest are of Middle Ordovician age. The Long Point Formation, of tate Middle Ordovician age, was inter- preted as a neoautochthonous cover, so that the Humber Arm altochton was emptaced in Middle Ordovician times. Rodgers (1965) later con- firmed the neoautochthonous nature of the Long Point. It should be noted, however, that, given the relationships described by Rodgers (1965) it was possible that the emplacement was later than the age of the Long Point since it is possible, if improbable, that the Long Point was transported on top of the Humber Arm allochthon. The likelihood of this possibility was lessened by Stevens (1970) who suggested that there might be a continuous section between the Table Head and the Long Point in the Mainland area of the Port-au- Port Peninsula though the critical part of the section was under the sea.
Rodgers and Neale (1963) concluded that the klippen could not have slid from the Long Range since the Precambrian rocks are surrounded by autochthonous rocks. A much more probable source lay east of White Bay in the Burlington Peninsula area. According to this view, the Humber Arm Supergroup is the unmetamorphosed equivalent of at least part of the Fleur de Lys Supergroup which must. if this is true, have been deformed and metamorphosed during or after the emplacement of the allochthons. An alternative view. also presented by Rodgers and Neale (1963). is that the Fleur de Lys is a Precambrian basement from which the allochthons slid. Much depends on the source of the allochthons and this matter will be discussed in more detail later.
Lilly (1964) urged caution in accepting the klippen hypothesis and commented that several other hypotheses were equally plausible given the information then available. Unfortunately Lilly, who had probably seen more of the rocks of west Newfoundland than any other geologist, never presented his ideas in detail. However, from incomplete manu- scripts (Lilly. 1967), compiled by W. Bruckner, it appears that Lilly thought that much of the Humber Arm was in place and older than the Carbonate rocks, although he did allow that some of the upper units could have been thrust from the west. Rodgers and Neale's (1963) klippen hypothesis stimulated a flurry of new work. Stevens (1965) mapped in the Humber Arm area and succeeded in dividing the Humber Arm rocks into several formations. He found fossils that suggested that the rocks ranged in age from early Cambrian to perhaps Middle Ordovician. Rocks much like the Green Point Series were found in the Tremadocian part of the succession. Spectacular melange zones, mapped as zones of chaotic deformation-, were found at the base of the atlochthon and at different horizons within it. They were interpreted as marking thrust zones so that the altochthon was constructed of several discrete slices. The melanges were thought to develop in zones of high hydrostatic pressure developed during movement. In such zones friction would be low. This interpretation of melange was at the time unusual since most workers interpreted such rocks as sedimentary deposits (Zen, 1961, Bruckner, 1966). Misled by the coarse grained nature of the lower and upper units of the Humber Arm, Stevens (1965) suggested that the Humber Arm largely formed in a deltaic environment. He did, however, confirm Rodgers and Neale's klippen hypothesis in the Humber Arm type area. Further evolution of thought on the geological evolution of west Newfoundland awaited developments in the realm of continental drift and plate tectonic theory. Early on, the former unity of the Appalachians and Caledonides was recognized by Wegener(1923) and Baitey (1927, 1929). Schuchert (1928), however, strongly denied any similarity and, as is well known, the hypothesis of Continental Drift passed into obscurity. Wilson (1962) suggested that the Cabot Fault and the Great Glen Fault of Scotland were once connected and analagous to the San Andreas Fault  in California. Church (1965) correlated the geology of the British Isles with that of Newfoundland. Perhaps his most significant correlation was that of the metamorphic rocks of the Scottish High- lands and Ireland with similar rocks on the Burlington Peninsula. Wilson published an important paper in 1966 in which he introduced the name "Proto Atlantic". Geologists studying the American Appalachians were reverting to Logan's view that the Appalachians somehow formed at an ancient continental margin (Drake et at, 1959; Dietz, 1963; Dietz and Holden, 1966). This concept was in agreement with the hypothesis of continental growth by the accretion of marginal orogens. These concepts were not popular outside North America for, in many other parts of the world, orogens seem to be intracratonic. Even in North America there were growing suspicions that the Appalachians had in fact an eastern craton and were not open to the Atlantic (Williams, 1964). How can orogens form at continental margins if they are bounded by older basement and some are intracratonic?
Wilson solved this dilemma by invoking ancient continental drift. He suggested that the Appalachian/Caledonian system is the suture zone in which a Proto Atlantic ocean was destroyed. Later continental drift has disrupted the orogen transposing parts of Paleo-Europe and Pateo-North America. For no good reason, Wilson shows the island arcs produced during the closure of the Proto Atlantic as fringing the North American Continent. As far as the writer is aware, it was W. Fritz who first suggested the possibility that the movement of the west Newfoundland allochthons was related to the closure of the Proto Atlantic. This suggestion was made in a private discussion after the writer had given a talk to the Logan Club of the Geological Survey of Canada on the geology of west Newfoundland. Unfortunately at the time he underrated its importance.
The whole matter of trans North Atlantic correlations was dis- cussed in detail at the Gander Conference (Kay, 1969), conceived and organized by Marshal Kay and convened in 1967. During this conference it became clear that there was overwhelming evidence that the Appalachians and the Catedonides were once part of the same orogenic belt and this paved the way for the later reinterpretation of Newfoundland geology in terms of the much better known geology of north west Europe.
At the Gander Conference, Stevens (1967a)reintroduced Murray's use of the term "ophiolite" for the Hare Bay and Bay of Islands Igneous Complexes but with no genetic implications. He also suggested that the Goose Cove Schists under the Hare Bay Complex were the equivalents of the Birchy Schists of the Fleur de Lys Supergroup (Church, 1969). This was thought to be evidence for the pre-Middle Ordovician deformation and metamorphism of the Fleur de Lys Supergroup as well as producing the first direct link between the geology of the Burlington Peninsula and that of west Newfoundland. Stevens (19671?) also demonstrated to the conferees the geology of the Humber Arm type section and a newly discovered section through the base of the allochthon north of The Gravels west of Stephenville.
The realization came in 1968 that the ophiolites did not in- trude the sediments on which they rest but were thrust sheets in their own right (Church and Stevens, 1968). This interpretation is self- evident in Hare Bay where Cooper (1937) had mapped the thrusts under the Goose Cove Schists. In the Bay of Islands area. the discovery of abundant detrital chromite and some serpentinite fragments in the Blow me Down Brook Formation under the igneous rocks and in the clastic rocks above the Table Head pointed to the same conclusion. The clastic sediments were, in part, derived from the ophiolites as they were transported. A field trip to Gaspe in 1968 (Stevens. ms. 1969) confirmed a suspicion that Logan's Tourell sandstones were analogous to the Blow me Down Brook Formation and are a ftysch deposit derived in part from an ophiotite source terraine. This also implied that the ophiolites were Arenig or older and not Devonian.
The similarity of the Quebec and Newfoundland ophiolite sequences to those of Papua (Davies. 1968). Cyprus (Gass. 1968) and Oman (Rein- hardt, 1969) was finally recognized in 1969 (Stevens et aL 1969). Since these ophiolites were described as oceanic crust and mantle sequences. it was logical to suggest that the Appalachian ophiolites had an oceanic origin.
This concept was expanded by Stevens (1969, 1970). After visiting the Gaspesian sections of the Quebec Group with J. Lajoie, C. Hubert, G. Middteton and R. Walker in 1969. it was realized that much of the Humber Arm Supergroup could be interpreted as part of a continental rise prism of deep water turbidites. If this were so, the autochthonous sequence would represent a continental shelf sucession. In 1969, the writer was not aware that this was Logan's original inter- pretation (Stevens, 1974).
In 1969, then, continental shelf and continental rise sediments had been recognized in west Newfoundland as well as probable oceanic crust and mantle. It was logical to try and incorporate these elements into a tectonic scheme based on Witson's concept of a Proto Atlantic. This was done in Stevens (1970). This paper made the following suggestions:
1. The geological relationships in west Newfoundland could be explained by assuming that the autochthonous sequence was a Cambro-Ordovician shelf sequence. The transported Humber Arm Supergroup was part of a continental rise prism. The Fleur de Lys Supergroup was the rest of the rise prism. The ophiolites were oceanic crust/mantle sequence that once floored part of Witson's Proto Atlantic.
2. After initiation in tate Proterozoic or Early Cambrian times, the ancient margin of North America remained essentially stable until latest Arenig times.
3. In late Arenig times, the shelf sequence was uplifted to give rise to the Table 'Head/St. George disconformity. At this same time flysch derived from the east appeared in the Humber Arm Supergroup. Late Arenig times, therefore, marked an important change in the history of the ancient continental margin in North America.
4. After this time the shelf broke up and sank. The rocks above the Table Head/St. George disconformity show a progressive in- crease in depth of deposition. Rocks much tike the Humber Arm formed and led some previous geologists to the belief that a11 of the Humber Arm Supergroup was in place. These fades changes are a striking example of the workings of Watther's law.
5. The ophiolites were a prime cause of movement of the Humber Arm Supergroup. As they moved westwards they peeled off packets of the rise sediments. Figure 6 of Stevens (1970) is not too dissimilar to recent diagrams of the structure of trench re- gions (e.g. Seely et a1_, 1974, fig. 2).
6. As the ophiolites moved westwards they shed detritus in front of them in the form of a flysch fan. This fan progressively migrated westwards and transgressed onto the now foundered shelf sequence during the Middle Ordovician. The movement of the allochthons was, therefore, a drawn out process, lasting several graptotite zones.
7. It seemed possible that the ophiolites of west Newfoundland once were continuous with those of the Burlington Peninsula so that it was possible that the deformation and metamorphism of the Fleur de Lys Supergroup was related to the ophiolite obduction. 8. Since detritus from the highest, ophiolite, sheet occurs in all of the internally derived flysch sequences it appears probable that the slice complex was progressively assembled and arrived at its final resting place in west Newfoundland in an already assembled condition.
9. In general, the stacking order of the slices reflects their paleogeographic position. The highest slice, the ophiolites, is farthest travelled and the lowest slices, locally parautochthonous shelf carbonates, are the least travelled. This again implies the slices were detached from their substrate in an order inverse to the stacking order.
Church and Stevens (1970, 1971) emphasized the oceanic origin of the Newfoundland ophiolites and suggested that they were emplaced as a result of the collision of the ancient margin of North America with a southeasterly dipping subduction zone. They drew a detailed com- parison between the ophiolite stratigraphy and the geophysical layering of modern ocean basins. According to this scheme the ultramafic rocks represent the upper mantle, the overlying gabbros and sheeted dikes represent layer 3 of the oceanic crust and the pillow lavas and sediments layers 2 and 1. The metamorphic rocks under the ophio- lites of west Newfoundland were thought to be produced either as a result of frictional heating during obduction or as a result of ob- duction of hot  (1000°C) ophiolite. This latter hypothesis would imply that the ophiolites were formed by sea floor spreading only shortly before obduction. This in turn opened the possibility that the ophiolites formed in a small ocean basin rather than in a major ocean basin such as the present Atlantic.
It was further suggested that some of the volcanic rocks of Notre Dame Bay were once continuous with the Bale Vert and Be ts Cove ophiolites but have an island arc complex built on them. The spectactular sheeted dyke unit of the Be ts Cove ophiolite was first recorded in this paper and, if the conclusions are correct, it is possible to study the Moho on land without deep drilling. Church (1972) later gave a more substantial account of the ophiolite problem.
Synchronous with the work at the University of Western Ontario. Dewey and Bird published an important series of papers on the same general problem (Dewey. 1969; Bird and Dewey, 1970; Dewey and Bird, 1971). These papers discussed the origin of the Appalachian/Cale- donian system in terms of plate tectonics, which then was only recently developed. Indeed, as far as the writer is aware, Dewey's 1969 paper was the first to apply plate tectonics to an ancient orogen. The earlier papers (Dewey, 1969; Bird and Dewey, 1970) differ from the interpretations of Church and Stevens in two main ways. The ophiolites found west of Notre Dame Bay were regarded as intrusive igneous bodies derived as diapirs from a subduction zone. The second point of difference concerned the polarity of subduction. According to Dewey (1969) and Bird and Dewey (1970) subduction was directed in a generally western direction, that is under the North American continent so that the ancient continental margin would have had the character of an Andean mountain range. This is difficult to accept since there are no post Lower Cambrian intrusions in west Newfound- land and terrestrial sedimentation did not commence in west Newfound- land until the late Silurian, early Devonian deposition of the Clam Bank Formation. The problem of polarity of subduction is explained in more detail in a later section.
By late 1971 Dewey and Bird (1971) had accepted the Stevens (1970) and Church and Stevens (1970, 1971) interpretation of the western ophiolites but suggested that they formed in a small ocean basin above a west dipping subduction zone.
Later works (Williams, 1971, 1972; Upadyuay et al, 1971; Williams and Malpas. 1972; Williams and Smyth. 1973; Norman and Strong, 1975; and Riccio, 1976) have substantially supported the oceanic origin of the western ophiolites. It is now also generally accepted that the sedimentary rocks of west Newfoundland represent a telescoped continental margin of Cambro-Ordovician age and that sedimentary and tectonic evolution of the region is somehow related to a cycle of birth and destruction of an Early Paleozoic ocean; that is, a Wilson Cycle.
The second part of this thesis is devoted to a discussion of the second generation of plate tectonic hypothesis based on the geology of west Newfoundland.