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  1. The evolution of Oppel's ‘Macrocephalusbett’ (Callovian, Middle Jurassic)
  2. The upper Bathonian ammonite zonation of East Siberia
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It is now known that the Camp Cove Formation is Triassic in age and the calcareous siltstones in which Brookfield found Dactylioceras are presumably part of the Harrison Lake Formation locality 7 of the West Road Member. The presence of Harpoceras and Phymatoceras in the Harrison Lake area is recorded for the first time in this report. Frebold collected specimens of this genus from the Harrison Lake area but he mis-identified them as the Lower Bajocian genus Fontannesia see Monger, ; Brookfield, Bajocian see Chap. At this locality Lilloettia lilloetensis was collected from steeply dipping sheared siltstone.

Locality 35 and section 1 locality 26 yielded specimens assigned to L. Fauna B8 is further divided into sub-faunas and locality 17A is assigned by the writer to the Lilloettia lilloetensis Fauna B8 c of Callomon , p. Fragments of Cadoceras macroconchs are most abundant, but identification to species level is impossible.

Five fairly complete specimens of Cadoceras comma IMLAY have been collected from this locality and two specimens described as Cadoceras Paracadoceras cf. Also placed in this Fauna B8 e by Callomon are the species C.

UBC Theses and Dissertations

The three species at locality 17 C. Overlapping age ranges for many of the species is common and Fauna B8 is divided into subfaunas based on the relative abundances of particular species. For example, C. Callomon , p. Pseudocadoceras grewingki, which occurs at localities 17 and 30, is not discussed with respect to its zonal affinity by Imlay or Callomon The age of Fauna B9 appears to be Middle Callovian, although definite proof is lacking Callomon, , p. Therefore, P. Another possiblity is that Fauna B9 is somewhat older; perhaps upper Early Callovian. About 10 to 15 m stratigraphically above locality 17 is locality 18 Fig.

One ammonite specimen resembles Cadoceras catostoma belonging to the C. Locality 18 is therefore assigned to the same faunal assemblage as locality Imlay , p. This higher assemblage is- described by Callomon as the Lilloettia stantoni Fauna B8 g and placed at the top of the C. Alaska is by far the richest area faunally with taxa of both the Boreal Cadoceras, C.

Paracadoceras , C. Stenocadoceras , Pseudocadoceras, Kepplerites and East Pacific Lilloettia, Xenocephalites realms along its southern coast. The Western Interior Region was the site of Early Callovian regression Callomon, and faunas from this region once described as Early Callovian Imlay, a , are now considered to be Bathonian Callomon, The Arctic Region yields few Lower Callovian ammonites and those present bear few similarities to faunas from the Cordilleran Region Imlay, b , but major features of the ammonite fauna from the Arctic Region are almost identical with those from East Greenland Callomon, suggesting deposition in the same broad Arctic Basin.

The western Cordillera contains Late Paleozoic and Triassic sections which are stratigraphically distinct. Many terranes have been postulated for the Cordilleran Region Coney et al. Ideas on transport distance and time of docking for these terranes are quite varied Davis et al. Recent work by Mortimer on the structure and stratigraphy of Quesnellia and Stikinia suggest a completely separate spatial evolution for these two terranes during the Late Triassic and Early Jurassic time with an intervening ocean basin Cache Creek Terrane at least km wide.

The position of Quesnellia by Middle Jurassic time may have been near or at its present position relative to the Omineca Crystalline Belt as Toarcian and Bajocian sediments within this terrane contain detrital white micas Tipper, , suggesting deposition near a metamorphic source i. It is also probable that the Quesnellia Terrane was a positive feature by Bathonian time as no deposits of a younger Jurassic age excluding a single occurrence of Lower Callovian conglomeratic sediments Tipper, personal communication are recorded Taylor et al.

The figures of Taylor et al. The Early Callovian Boreal faunas on Peninsular, Wrangellia and Stikinia suggest that these terranes could not have come from much further south than Oregon because the Callovian Boreal-Tethyan boundary occurs about this latitude on the craton. This could equally imply that the terranes have not been displaced from their present position, but Early Callovian faunas from Alaska contain rare specimens of possible Tethyan affinity e. Reineckeia together with abundant Boreal faunas.

This would suggest that the Peninsular terrane, although still in Boreal latitudes, was closer to the Boreal-Tethyan boundary in Callovian time and may have moved somewhat northward. Locality 15, which is situated on the southwest shore of Cascade Peninsula Fig. Brookfield recovered mainly Cardioceras and Oxytoma from this locality and rare Lingula sp.

Phylloceras sp. The ammonite Phylloceras was also found at this locality by Crickmay a. This Fauna B12 is "close to if not identical with" the C. B13 C spintfenm B12 C martin Figure Early Oxfordian faunal successions for the Western Interior and Cordillera regions together with equivalent European faunal subzones modified from Callomon, Locality 15 which is assigned to Fauna B12 Fig. Associated with C.

Although rare at this locality C. It appears to be roughly equivalent to Callomon's Cardioceras spiniferum Fauna B13 of the Cordilleran Region which is found in the upper Bukowskii to lower Costicardia subzones Fig. This ammonite species belongs in the C. The ammonites present at the two localities show that locality 15 Bukowskii Subzone is slightly older than locality 20 lower Costicardia Subzone.

The two specimens of C. Their migration southwards, presumably to occupy ecologic niches abandoned by other ammonite families due to the preceding Callovian regression Hallam, , led to faunal similarities between the Cordilleran and the Western Interior regions by Early Oxfordian Imlay, The genus Cardioceras is common in both regions and although some species and genera are confined to one region, many are found in both Imlay, ; ; The Early Oxfordian ammonites of the Western Interior Region lived in a shallow sea extending as far inland as Wyoming and parts of adjoining states Imlay, ; and possibly included Colorado and northern New Mexico Hallam, This shallow sea was called the Logan Sea by Schuchert now called the Sundance Sea and it was believed to be separated from the open ocean to the west by mountains which joined the craton to the south Schuchert, This bordering landmass to the west was -called "Jurozephyria" by Crickmay and is termed the Mesocordilleran Geanticline by Armstrong and Ward in prep.

Armstrong and Ward in prep. Neither hypothesis can be proven but the faunal similarities suggest that a marine connection did exist between the two regions in Early Oxfordian time. Faunal similarities and differences between the two regions indicate possible physical and climatic barriers were in effect.

The presence of Phylloceras in an area probably indicates access to the open ocean Callomon, ; Taylor et al. A climatic barrier was almost certainly in effect between these two regions as Boreal faunas are not found around Mexico and Tethyan faunas are rare in the Western Interior Region. It is also possible that the Tethyan forms accessed the Western Interior Region through a seaway farther north, possibly near Oregon as Oxfordian marine rocks are present in the northeast corner of the state Fig. Samples of Cretaceous fossils from both Peninsula and Brokenback Hill formations were collected and sent to Dr.

Jeletzky for identification. TITH in Buchia cf. A period of uplift, erosion and probable deformation, Crickmay's Agassiz Orogeny followed deposition of the Early Oxfordian Billhook Creek Formation. It was during this time in the Late Jurassic that the Kent Formation was probably deposited. Uplift led to the erosion of plutons, which supplied granitic material to the Peninsula Formation. The basal conglomerate of this formation has not been dated, but immediately above are sandstones replete with Buchia.

Section 3 locality 43 on fig. The lowest in the section C yielded exclusively Buchia uncitoides s. Locality C of section 3 is 37 m stratigraphically above C Fig. These faunas indicate an age in the uppermost part of the B. The highest collection of Buchia made at section 3 was from C This locality is dominated by large forms of B.

Rare forms of B. There is no evidence for faulting or overturning of this section. The most probable reason for the discrepancy in age for C is an error in collecting. Ages based on Buchia are obtained by comparing the relative abundances of particular species and it is possible that this collection did not give a representative view of the Buchia population at this locality. The remainder of the localities along section 3 appear to conform well to the zonal scheme of Jeletzky ; Buchia faunas from isolated localities within the Peninsula Formation were also collected Fig.

Localities 32 and 40 yielded Buchia of Lower Berriasian B. Locality 40 yielded Buchia of the same species as that from C in section 3 and was probably derived from the same bed Jeletzky, written communication. Faunas of Middle Berriasian age [B. The first two localities 14 and 22 are equivalent to C lower B.

The other localities are younger than 14 and 22 but are still within the B. All contain abundant specimens of B. Localities 31 and 33 also yielded B. The genus Buchia uncitoides var. The youngest fossils found in the Peninsula Formation were collected from beneath a powerline tower, m southwest of the fire lookout on Brokenback Hill at locality 28 Fig.

Two collections were made at this locality about 3 m apart stratigraphically. This collection was placed in the topmost part of the Buchia tolmatschowi Zone Fig.

The Hidden Underwater Geography of Newfoundland Canada

The collection from the overlying locality C contains predominately B. Jeletzky placed this fauna into the basal part of the. Buchia pacifica Zone of Early Valanginian age. In Long Island Bay along the west shore of Long Island, strongly deformed Buchia shells were collected from locality Jeletzky identified them as either B. The age can accordingly range from late Berriasian to late Valanginian. The rocks along the southwest side of Long Island including locality 23, have been assigned to Brokenback Hill Formation by the writer.

Locality 24, located on a small island in Long Island Bay, yielded stronglj' deformed Buchia from a phyllite. Unlike locality 23, several specimens could be assigned to B. This locality is therefore assigned to some part of the B. The B. This genus is facies tolerant Jeletzky, ; , p. The overlying zone in the Harrison Lake section is rich with B. Its abundance in California compared with the scarcity of B.

Faunas of the B. Crickmay's ; a three species of Buchia "A. They are all found in the Harrison Lake area, although B. The youngest rocks of the Peninsula Formation are found at locality 28 and represent the upper B. The overlying B. Areas in the Canadian Cordillera where the B. Locality 24 was also tentatively placed in the B. The rocks of this locality are highly deformed and it can only be said that they belong to the Peninsula or Brokenback Hill formations.

If the rocks do in fact belong to the Peninsula Formation, then they have been thrust up over Brokenback Hill Formation which lies along the southwest shore of Long Island Fig. The oldest locality within the Brokenback Hill Formation excluding the possible locality 24 occurs on the southeast shore of Cascade Peninsula at localities 12 and Faunas at localities 12 and 13 are Upper Valanginian, lower part of the Buchia crassicollis Zone Fig.

Fossil localities within Brokenback Hill Formation along the west side of Harrison Lake are rare and isolated. This species was recently described from northeastern Siberia, where they are confined to Late Hauterivian rocks, but range into Early Hauterivian rocks in the Taseko Lakes area Jeletzky, written communication.

The evolution of Oppel's ‘Macrocephalusbett’ (Callovian, Middle Jurassic)

Therfore, these two localities can only be dated as of a general Hauterivian age. At locality 47 two specimens of Homolsomites Wellsia cf. Jeletzky believes these belong to some part of the Homolsomites packardi Zone of Early Hauterivian age Fig. A single ammonite specimen from locally derived float at locality 55 near Doctor's Point was submitted by G. Tipper of the Geological Survey of Canada for identification.

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The only other locality in Brokenback Hill Formation which yielded identifiable fossils is locality 49 where an ammonite identified by the writer as Ammonoceratites sp. It closely resembles the specimen figured in McLearn , pi. The remaining localities not discussed yet 45, 48, yielded belemnites or ammonites too poorly preserved for identification.

Correlations and Paleobiogeography: The B. On the west coast of Vancouver Island the B. This zone is the oldest Cretaceous zone known from the San Juan Islands Spieden Island and Homolsomites quatsinoensis is found in both areas. In the Harrison Lake and Nooksack areas the B. To the north, isolated localities belonging in the B. In California a possible hiatus existed during the B. The Hauterivian Inoceramus paraketzovi from localities 44 and 46 are not common in the western Cordillera but they are known from the Taseko Lakes area as stated earlier.

The Early Hauterivian Homolsomites packardi Zone, which locality 47 belongs in, was first described from Oregon Imlay, , p. The discovery of Cleoniceras Grycia? Rocks of the Gambier Group were previously thought to be restricted to the poorly understood mid-Cretceous Gambier Basin see Jeletzky, a. The C. The presence of the C. The age of the presumably stratigraphically older Ammonoceratites sp. The wide extent of the C. Marine sediments continued to be deposited in the Tyaughton-Methow Trough until the end of the Albian and at some point in the Turonian it became an elevated source area Jeletzky, b.

This marked the end of marine sedimentation in the Harrison Lake area which was situated along the western margin of the Tyaughton Trough adjacent to the now elevated Coast Plutonic Complex. The new Middle Triassic age for the Camp Cove Formation makes this correlation less certain but it may be equivalent to an as yet undated older section of the Cultus Formation or a younger part of the Chilliwack Group, removed by erosion in the Chilliwack Valley. The formation is roughly age equivalent to basalt and turbidite flows siltstone, sandstone, conglomerate of the Triassic Cadwallader Group Rusmore, , lying km to the north-northwest; Monger speculatively correlated the Slollicum assemblage Fig.

To the east in the Coquihalla area, the Lower to Middle? Triassic Spider Peak Formation, composed of greenstone, gabbro plus minor tuff, siltstone and sandstone, outcrops locally along the Hozameen Fault O'Brien, and is age equivalent with the Camp Cove Formation. These two formations, on the basis of age, can be correlated in part with Permian to Middle Jurassic chert, siltstone, basalt, ultramafics and minor carbonates of the Bridge River-Hozameen assemblage which is believed to represent oceanic crust and overlying sediments.

Presence of these clasts in the Celia Cove Member suggest a stratigraphic linkage existed between the Harrison assemblage and Chilliwack-Cultus assemblage by Early Toarcian time Monger, Provenance of the pale green chert clasts of Middle Triassic age based on radiolaria and conodonts is difficult to determine. The Bridge River Group lying to the east represented an ocean basin until the Middle Jurassic as indicated by radiolaria of this age recovered from chert. It is unlikely that this unit could be the source for the chert clasts because it was not uplifted until mid-Cretaceous time Coates, Pale green chert silicified tuff of Permian age is known from the Chilliwack Group Monger, and perhaps undated beds as young as Triassic are present or were present prior to erosion?

Another possible source for the chert is the Elbow Lake Formation of Washington with Permian to Jurassic ribbon chert and tholeiitic basalt of oceanic affinity Brown, As the Early Permian limestone clasts are possibly derived from the Chilliwack Group to the south, it seems probable that the chert clasts likewise have a provenance to the south, possibly the Chilliwack Group or Elbow Lake Formation. This suggests a hiatus at the Triassic-Jurassic boundary in this area.

The flysch-like sediments of the Cultus Formation Misch, ; Monger, contain Late Triassic Norian and Early Jurassic Pliensbachian fossils, but a continuous section across the Triassic-Jurassic boundary can not be concluded from this. The same argument is true for oceanic sediments of the Bridge River and Hozameen groups which contain Middle Norian and Pliensbachian radiolaria Potter, The overlying flows, tuffs, pyroclastic rocks and minor sediments of the Weaver Lake and Echo Island members has marked lithologic similarities to age equivalent andesite to dacite flows, breccias and intercalated sediments of the Wells Creek volcanics in Washington Danner, ; Misch, They are also age equivalent to Toarcian?

The Early Oxfordian volcaniclastic rocks and sandstones of the Billhook Creek Formation are age equivalent to siltstones and shales of the Relay Mountain Group but volcanic material of this age is uncommon in British Columbia. It is during this hiatus that the Agassiz Orogeny Crickmay, , discussed in Chapter 2, occurred which disrupted older units in the area. The volcanic section of the Brokenback Hill Formation is lithologically similar to and age equivalent with the Gambier Group to the west Ray et al. Minor volcanic rocks are also known in the Fire Lake Group Roddick, At the base of the Gambier Group and the Peninsula Formation are basal conglomerates rich with granitic clasts and the implications of this will be discussed in the next section.

Three belts Insular, Intermontane, Foreland consist of unmetamorphosed and low grade metamorphic rocks Fig. Separating these three belts are higher grade metamorphic and plutonic rocks of the Coast Belt, in which the Harrison Lake assemblage is situated, and Omineca Belt which are described by Monger et al. The accretionary history of these belts and the terranes within them are discussed further by Monger and Price , Coney et al. The western margin of North America was a passive continental margin from latest Precambrian through much of Paleozoic time Coney et al.

In latest Triassic to Middle Jurassic the western boundary of the North American Plate changed to a convergent and transform regime. Late Cretaceous emplacement of these terranes into their present position along the continental margin Peninsular, Wrangellia, Stikinia, Northwest Cascades System is the result of oblique or transform motion between North America and the Farallon or Kula plate Engebretson et al.

This site would later become the locus of the Tj'aughton-Methow Trough in the Jurassic. Georgia Strait. A possible age equivalent arc may have been situated along the eastern margin of this basin as suggested by the presence of volcanic rocks of the Dewdney Creek Formation. How these arcs formed is not known, but one possibility would be both western and eastern subduction of the oceanic crust Bridge River-Hozameen assemblage followed by final closure of the basin perhaps in a way similar to that shown by Monger , fig. A regionally extensive hiatus above the rocks of these volcanic arcs, spans Late Bajocian and Bathonian time Frebold and Tipper, This is about the same time as the initial opening of the North Atlantic Ocean and the hiatus may reflect a change in motions of the North American Plate relative to plates flooring the Pacific Ocean Monger and Price, Sedimentation following this hiatus began again in Callovian to Oxfordian time Fig.

Local uplift and erosion during this hiatus unroofed plutons that may have been associated with the Middle Jurassic volcanic arc along the western margin of the basin. These plutons were the source for granitic material found in the basal conglomerates of the Gambier Group and Peninsula Formation which were situated on the west and east side of the developing Coast Plutonic Complex.

Volcanic activity resumed along this western arc in the Early Cretaceous as shown by the presence of flows and pyroclastic rocks in the Gambier Group Hauterivian to Barremian Roddick, and Brokenback Hill Formation Late Valanginian to Middle Albian. The Albian marked the last marine transgression over much of the region and faunas of this age are recorded from isolated localities throughout the Tyaughton-Methow Trough and the Georgia Basin Gambier Group see Chap. Marine sedimentation continued in the Tyaughton-Methow Trough through Albian time with sources from both the west and east Coates, , but by the end of this stage the trough ceased to exsist as a marine basin Jeletzky, b due to infilling, uplift and regression.

Mid-Cretaceous non-marine sediments e. Source for these sediments was from the east Spences Bridge volcanic arc and the west uplifted Bridge River and Hozameen groups Coates, This was followed by transtensional faulting along the Fraser River-Straight Creek fault system in Late Eocene time, which disrupted the earlier structures Monger, Donovan et al. Remarks: The genus is evolute with bifurcating, usually straight ribs that pass over the venter rectiradiately or with a gentle forward inclination. Plate 1, Figure 1, 2. Material: Five poorly preserved specimens in a dark grey calcareous siltstone.

Description: Evolute; ribs are rectiradiate, straight and begin about the umbilical wall. Some primaries bifurcate in upper flank region but poor preservation makes this difficult to see. There are about 23 ribs per half whorl at a diameter of 34 mm. Discussion: The specimens are very poorly preserved making species designation impossible. Occurrence: Dactylioceras sp. Age: Middle Toarcian. Remarks: Midvolute; flanks flat to gently convex.

Sharp umbilical shoulder and venter, which is unicarinate. Falcoid ribs, which become stronger on upper part of flank. Harpoceras sp. Plate 1, Figure Material: About 18 specimens poorly preserved as molds in a dark grey calcareous siltstone. Description: Fairly involute; shell expands rapidly. Strong falcoid ribs begin at umbilical wall;, at mid-flank primaries bifurcate.

Intercalated secondaries are common. Ribs are moderately spaced.

Occurrence: Found associated with Dactylioceras sp. Remarks: Fairty evolute genus with nearly straight rectiradiate ribbing, which commonly projects onto the venter from the ventrolateral shoulder. Dumortieria cf. Material: Seven secondarily compressed but identifiable specimens and about 25 poorly preserved specimens found in a brown, non-calcareous shale and calcareous siltstone. Ribs are fairly sharp, rectiradiate and begin on the umbilical wall. In smaller specimens and inner whorls of larger ones, the ribs are straight and rectiradiate until the upper flank where they flex adorally.

In the later whorls of larger specimens, however, the ribs are more gently curved, beginning on the mid or upper flank. Number of ribs per half whorl increases with increasing size Fig. Ribs end on the venter just before the low keel which is poorly preserved in specimen C PI. Discussion: The specimens of D.

Occurrence: D. It is not recorded from western Canada previously, but similar species D. Insignlsimllis A this report D. Material: Seven moderately preserved specimens and about 20 poorly preserved specimens found in a brown, non-calcareous shale and calcareous siltstone.

A poorly preserved low keel can be seen on some of the specimens. Rectiradiate ribs begin on the umbilical wall and are straight until the upper flank, where they flex adorally. The ribs taper and fade as they cross the ventro-lateral shoulder. Ribs are fairly distant, averaging about 14 ribs per half whorl at a diameter of 20 mm. On larger specimens PI. Discussion: The specimens are very similar in ribbing and volution to D.

The more distant ribbing on the outer whorls of the two larger specimens mentioned earlier differs from other large figured specimens. This may simply be a variation in ribbing within this sample population. Occurrence: Found with D. The locality j'ields predominately ammonites with rare bivalves two in this collection. A specimen that resembles D. Remarks: Evolute; planulate whorl shape with flat to carinate-bisulcate venter. Ribs are sigmoidal and commonly branch out in twos and threes from tubercles on the umbilical edge.

Phymatoceras sp. Plate 2, Figure 1. Material: One poorly preserved specimen in grey calcareous siltstone. Some tubercles can be seen near the umbilical shoulder but the specimen is too poorly preserved for better identification. Occurrence: Found at locality 7 with Dactylioceras sp. Phymatoceras is also found in the Spatsizi Group Thomson et al. Remarks: Evolute; planulate; whorl section rounded to subrectangular. Keel present; lateral spines or tubercles may be present. Long primary ribs and more or less projecting secondaries. Septal suture as in Hammatoceras. Podagrosiceras lacks a keel, has alternating ribs on the venter and suture patterns of the two genera differ Westermann, b; Poulton and Tipper, in prep.

Plate 2, Figure 2. Material: One very poorly preserved specimen in brown shale. Description: Evolute; umbilical wall steep and may be undercut.

The upper Bathonian ammonite zonation of East Siberia

Flanks broad and gently convex; poorly preserved keel noted. Ribs begin on umbilical wall, are prorsiradiate until the lower flank and then curve becoming rectiradiate. No tubercles are noted but this ma3' be due to the specimens poor preservation. Occurrence: Found at locality 3 with abundant pectinid bivalves and rare belemnites.

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This locality lies in the uppermost part of the West Road Member. Age: Early Late Aalenian. Remarks: The type species L. The genus is involute. Inner whorls are finely to moderately ribbed, but on later whorls, ribbing begins to fade and mature whorls are smooth. The genus Lilloettia has been synonymized with Arctocephalites Spath, , p. It has been considered to range from the Middle Bathonian Westermann, to Middle Callovian Imlaj', b; Frebold and Tipper, , but a recent reassessment by Callomon indicates that assignment to the early Lower Callovian is a more reasonable interpretation of the -data based on regional faunal associations from Alaska to Oregon.

It is characteristic of the East Pacific Realm Taylor et al. Material: Three internal molds from sheared siltstone locality 17 A and two poorly preserved external molds localities 26 and 35 from Fine grained sandstone. Flanks gently convex; venter is plain and inflated. Ribs are faint on umbilical shoulder and rectiradiate. They become stronger on lower flank and flex prorsiradiately. About mid-flank or slightly above, the primary ribs bifurcate; very few remain single to the venter.

Intercalated' secondaries are common and begin around the furcation points. Ribs pass over the venter, where they flex gently prorsiradiately. Suture line is not preserved. The specimens were collected from locality 17A, which lies about 10 to 15 metres stratigraphically beneath locality 17 where Cadoceras comma and Pseudocadoceras grewingki were collected. The latter locality belongs in Callomon's Fauna B8 e. Therefore, these localities agree well with the faunal assemblage zones of Callomon Single poorly preserved specimens assigned to L.

D14, pi. Flanks gently convex. Ribs sinuous; beginning just below umbilical shoulder, they gently incline rursiradiately until the middle of the lower flank at which point they curve forward becoming prorsiradiate. Primaries bifurcate in mid-flank area; the secondaries bend slightly posteriorly and continue over the plain venter. Primaries are strong and triangular in section; secondaries do not fade but become narrower and more angular in section than primaries. Only two of the secondary ribs are not well attached at a furcation point.

Suture line can not be seen. Discussion: L. Occurrence: Lilloettia stantoni was collected from locality 1 Crickmay's locality 8, on the south shore of Harrison River from the Mysterious Creek Formation. Lilloettia sp. Plate 2, Figure 8 Material: Single fragment found in float showing venter and part of flank. Description: Umbilicus not seen on specimen but it was probably very narrow. Whorl is higher than wide; ellipsoidal in shape and venter is slightly inflated. Primary ribs incline prorsiradiately and bifurcate about mid-flank but one primary remains single to the venter and is flanked by an interecalated secondary rib.

From furcation point, ribs flex slightly posteriorly and thicken somewhat as the3' cross over the venter; they are separated by interspaces of similar width. Ribbing is also similar to L. Occurrence: Collected at the feet level in the Billhook Creek valley from locality Age: Early Callovian. Remarks: Inner and middle whorls well ribbed, becoming smooth on later whorls. Tubercles are sometimes present. Diagnostic characteristic of this genus is a sharp umbilical shoulder on mature whorls. Age and Distribution: Cadoceras is common over much of northern and central Europe, Russia, Arctic Islands and localities along the western edge of North America from southern Alaska to California.

The genus is characteristic of the Boreal Realm Taylor et al. Material: Seven specimens from two localities; four represent mature growth stage. Umbilicus narrow and deep; wall steep and high especially on outer whorls. Umbilical shoulder curved on inner whorls and angular in adult stages. Flanks gently curve on inner whorls to an inflated, plain venter; flanks on outer whorls indistinguishable from convex venter. Ribs are strong and fairly distant 13 primary ribs per half whorl on inner and intermediate whorls.

They begin on umbilical wall and pass prorsiradiately onto the lower flank where they bifurcate into strong secondaries which flex. Changes in ribbing occur during growth. Furcation points become indistinct and some intercalary ribs begin to appear; the venter and then flanks become smooth some striae can be seen leaving only coarse umbilical swellings across the umbilical shoulder. The suture line is not preserved in any of the specimens.

Discussion: Imlay b states that "this species is characterized by its globose, coronate form, by coarse ribbing that passes into striae on the last two whorls and by the persistence of comma-shaped swellings on the umbilical edge. There are also marked similarities between C. A zonal scheme set up by Imlay placed C. This zone has been abandoned and replaced by the Cadoceras comma Fauna B8 assemblage for reasons discussed by Callomon , p. Its age, however, remains Lower Callovian.

The species C. Occurrence: C. Plate 3, Figure 6 Material: Single specimen at locality 26 preserved in a fine grained sandstone. Flanks very slightly convex and venter is rounded. Umbilicus moderately deep and wall is steep. Ribs begin on umbilical wall, are prorsiradiate until the umbilical shoulder where they curve becoming rursiradiate and continue onto the flanks. They commonly bifurcate about mid-flank and continue simply over the venter.

Discussion: This specimen is an immature Cadoceras sp. Adult forms have a very angular umbilical shoulder, coronate whorl shape and commonly are smooth on outer whorls. Occurrence: Found at locality 26 section 1 associated with Pseudocadoceras grewingki, Lilloettia lilloetensis and trigoniid bivalves. Material: One immature specimen from grey to black shale. Umbilical wall low and steep on inner whorls; becomes much higher before end of last whorl then lowers again. Slightly ovate whorl shape; wider than high on last whorl. Ribs begin low on umbilical wall and project rectiradiately or gently rursiradiately towards umbilical shoulder at which point they curve anteriorly and become prorsiradiate.

Just below mid-flank the primaries may bifurcate, however, some primaries remain single. Intercalated ribs are present and begin about mid-flank. Ribs continue up flanks and cross over venter where they arch gently forward. Crickmay ; a discussed C. Occurrence: Locality 18 from which C. These species are found together Imlay, b in the lower two thirds of the Chinitna Formation, Alaska and in the lower member of the Shelikof Formation, Alaska.

Whor l width widest at umbil ical shoulder. Umbil icus deep and moderately narrow; wal l low and gently inclined on inner whorls, becoming steeper and higher on later whorls. Umbi l ica l shoulder strongly curved; flanks gently curve onto an arched venter on inner whorls or a rounded venter on outer whorls. Ribs begin part way down umbilical wal l. They project straight up and flex anteriorly at umbil ical shoulder onto the flanks. Ribs are gently prorsiradiate across flanks; at mid-flank primaries bifurcate although some remain single; intercalated secondaries are present.

Ribs continue up flanks and cross over venter on inner whorls but begin to fade on venter and flanks of last whorl leaving only swellings on umbil ical shoulder. Suture line can not be traced. It differs from C. Associated faunas at this locality include C. These three species are also found together in the lower part of Chinitna Formation, Alaska Imlay, b although not from the same localities. Locality 17 is placed into Fauna B8 e of Callomon based on the presence of C.

Remarks: Moderately involute; shell compressed at all stages. Ribs are sharp and present on all whorls. Differs from Cadoceras and Paracadoceras by being less evolute and having a less rounded whorl shape. Secondary ribs project more strongly forward on Pseudocadoceras. Its age ranges from Lower to Middle Callovian. D21, pi. Material: Twenty or more fragments and complete specimens preserved in a calcareous siltstone. Many specimens have been distorted to some degree in the plane of coiling. Whorl shape ellipsoidal, being slightly higher than wide; widest on lower to mid-flank.

Umbilicus fairly shallow and moderately wide. Umbilical wall low and moderately steep on inner whorls; becomes higher and more steep on outer whorls. Flanks are slightly convex and round onto a plain venter. Flattening in plane of coiling has distorted the whorl shapes of some specimens and exaggerated umbilical depths. Ribs begin about the middle of umbilical wall inclining rursiradiately.

At umbilical shoulder they flex prorsiradiately onto flanks. About mid-flank, some primaries bifurcate; this occurs more frequently on the outer whorls. Some secondaries are only loosely attached at a furcation point; still others remain unattached. These unattached secondaries usually separate two non-bifurcating primary ribs. At ventro-lateral shoulder, ribs thicken slightly and project onto venter. Ribs are fine and closely spaced on inner whorls, becoming stronger, sharper and more widely spaced on outer whorls. Suture' can not be seen on any of the specimens. The two species are also found together in Chinitna Formation Imlay, b at U.

Mesozoic localities , , , , , , and and from isolated localities in the Shelikof Formation, Alaska. Remarks: Cardioceras has a keeled venter. Whorl shape is moderaterly compressed. Ribs are well differentiated and scondaries strongly project anteriorly onto venter. The genus is further divided into several sub-genera. D15, pi. Description: Umbilicus fairly narrow; wall low, moderately steep. Flanks very gently curving almost flat ; ventro-lateral shoulder curves onto a keeled venter which is fairly high and serrated.

Whorls are moderately expanding and whorl shape is lanceolate. Ribs begin on umbilical wall inclining gently rursiradiately to umbilical shoulder where they curve slightly to become rectiradiate. They are moderately sharp but low; at mid-flank most primaries bifurcate, especially on the more immature whorls. The more posterior of the bifurcating ribs commonly arches back forming a sickle-like shape as it crosses the upper half of the flank. The anterior rib is usually straighter but may flex somewhat.

At ventro-lateral shoulder the ribs curve sharply anteriorly onto venter; some secondaries may again fork on venter C, PI. Ribs cross over keel forming an anteriorly pointing chevron pattern when looking down on the venter. It also closely resembles the somewhat problematic species C. The two species would perhaps be better described under the single species C. It is the dominant species at this locality, but two specimens of C.

The species is also found in France Maire, Material: Eight specimens from two localities 15 and 20 preserved as internal and external molds in siltstone and sandstone. Flanks flat; curved ventro-lateral shoulder and a sharp, high keel. Whorl shape is ogival with the addition of a keel. Ribs are moderately distant and begin on umbilical wall. They are rectiradiate until the umbilical shoulder where they curve onto the flanks becoming prorsiradiate. In mid-flank area the ribs become higher; an elongated node-like projection becomes prominent on some primary ribs. This persists until the furcation point where ribs become lower but still remain fairly sharp.

Some ribs bifurcate, but many remain single and are separated by one or two intercalary ribs. On the upper flank, ribs begin to curve more strongly forward; at ventro-lateral shoulder ribs project strongly forward onto venter and cross over keel forming an anteriorly pointing chevron pattern when looking down onto the venter. No suture line is preserved. Discussion: A ll specimens of C.

Also, the furcation points start slightly higher on the flanks of C. A specimen figured as C. The writer feels Imlay's assignment is better as the pattern of secondary ribs more closly resembles C. Occurrence: Cardioceras Cardioceras hyatti has not been reported from Harrison Lake area previously. It is associated with C. Also at this locality are abundant bivalves, including Pinna. At locality 15 two specimens of C. Material: Three specimens preserved as internal and external molds in a medium to coarse grained green calcareous sandstone. Umbilical shoulder round; flanks are gently convex and curve over ventro-lateral shoulder onto a keeled venter.

Shell compressed; whorl shape difficult to distinguish, perhaps lanceolate but with a sharper ventro-lateral shoulder. Ribs are distant; primaries begin part way up umbilical wall. They are rectiradiate to slightly rursiradiate until the umbilical shoulder where they knee sharply forward to become prorsiradiate. Ribs are fairly high and sharp; they continue straight to slightly flexed until just above mid-flank where the primaries end in an elongated node. Most bifurcate although a few may continue single onto venter. Intercalated secondaries are common; the secondary ribs remain fairly strong although not quite as high as the primaries.

At ventro-lateral shoulder ribs curve sharply anteriorly then climb over the sharp keel giving it a serated or chevron-like appearence. Discussion: Cardioceras Cardioceras lillooetense was originally described from Cardt'oceras-bearing beds at the head of Big Creek, Lillooet, British Columbia Reeside, , p.

It is characterized by its distant primaries, which are high and sharp, and elongated nodes found at furcation points. It has also been found near Smithers and Lillooet, British Columbia. Cardioceras sp. Plate 4, Figure, Material: One incomplete specimen preserved as an external mold in calcareous shale and siltstone.

Description: Moderately evolute; vertical umbilical wall. Ribs begin on umbilical wall and incline anteriorly at umbilical shoulder. Ventral area not preserved. Ribs fairly distant and broad, becoming even more so on later whorls. Discussion: The specimen resembles C. Occurrence: Found with Cardioceras Scarburgiceras martini and two specimens of Cardioceras Cardioceras hyatti at locality 15 on Cascade Peninsula.

The emphasis of this study was to update and determine the lithostratigraphy, biostratigraphy, age, nomenclature and possible environmental setting of the rocks on the west side of Harrison Lake and to re-map the study area which has not been regionally mapped since Crickmay Regional correlations with other rock units are sugggested and possible paleogeographic settings discussed.

The oldest rock unit in this section is the Camp Cove Formation which has now been accurately dated as Middle Triassic based on both radiolaria and conodonts. A regionally extensive unconformity separates this formation from the overlying Harrison Lake Formation of Pliensbachian? Bajocian age. This formation has been divided into four members and includes Crickmay's previously described Echo Island Formation. The four members are the Celia Cove Member Pliensbachian?

Nine ammonite genera of Jurassic age were identified by the writer and many specimens could be identified to specific level despite the generally poor preservation. Currently there is no zonation for Toarcian faunas of North America, but Callomon has proposed faunal assemblage zones for some Middle and Late Jurassic stages and the Early Callovian and Early Oxfordian faunas of the Harrison Lake area correlate well with the faunal assemblages for his Cordillera Region fig. These faunas in the Mysterious Creek and Billhook Creek formations are very similar to faunas to the north and south in the Cordillera Region, including southern Alaska, north-central British Columbia Bowser Basin , Oregon and California.

The Early Cretaceous Peninsula and Brokenback Hill formations contain faunas very similar to faunas in the correlative Gambier and Fire Lake groups and together these units represent an overlap assemblage which links Wrangellia to Jurassic and older rocks of the Harrison Lake assemblage by Early Cretaceous time. Triassic-Jurassic ocean basin which is represented in its axial region by the Bridge River-Hozameen assemblage. Closure of this basin, possibly by both eastern and western subduction, may have started in Middle Jurassic time; the shrinking basin becoming the locus for Callovian to Albian marine sedimentation into the Tyaughton-Methow Trough.

By the end of the Albian, the trough ceased to exist as a marine basin due to infilling, uplift and regression. Rocks of the Tyaughton-Methow Trough and surrounding region were subsequently disrupted by transpressional faulting in post-Albian to pre-Eocene time and Late Eocene transtensional faulting. Oceanic crust and arc-trench gap tectonics in southwestern British Columbia. Geology, V. Jurassic geology of the world: London, Oliver and Boyd, p. Mesozoic Ammonoidea. Late Triassic to earliest Eocene magmatism in the North American cordillera: implications for the Western Interior basin.

Geological Association of Canada, Special Paper. Thesis, University of British Columbia, Vancouver, 50p. Low grade metamorphism of Permian to Early Cretaceous volcanic and volcaniclastic rocks near Chilliwack, British Columbia. University of British Columbia, Vancouver, 51p. Canadian Journal of Earth Sciences, V. Structural geology and accretionary history of the northwest Cascades system, Washington and British Columbia. Geological Society of America Bulletin, V. Monograph of the ammonites of the inferior oolite series.

Palaeontographical Society of London; p. Type ammonites: London , V. Geology of Hope area, British Columbia. Geological Survey of Canada, Map A. Geological Association of Canada Special Paper 27, pp. Geological Survey of Canada, Bulletin , 49p. Geology of the White Lake Basin. Geology of the Manning Park area, British Columbia.

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Geological Survey of Canada, Bulletin , p. Whitehorse district, Yukon. Geological - Survey of Canada, Memoir , 63p. Cordilleran suspect terranes. Nature, V. Compte Rendu Academie des Sciences Paris, t. The geology and paleontology of the Harrison Lake District, British Columbia, together with a general review of the Jurassic faunas and stratigraphy of western North America. Thesis, Stanford University, Stanford, California, p. Fossils from Harrison Lake area, British Columbia. National Museum of Canada, Bulletin 63, pp. Geological Magazine, V. Jurassic history of North America and its bearing on the development of continental structure.

Proceedings of the American Philosophical Society, V. Gross stratigraphy of Harrison Lake area, British Columbia. Published by author article 8.

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An introduction to the stratigraphy of southwestern British Columbia and northwestern Washington, in Guidebook for geological field trips in southwestern British Columbia. Geological Society of America, Cordilleran section annual meeting, pp. The Liassic ammonite zones and subzones of the north-west European Province. Eclogae Geol. Helvetiae, V. Paleontologie franchise, terrains jurassiques, Part 1, Cephalopodes: Masson, Paris, p.

Etudes paleontoloques sur les depots jurassiques du Bassin du Rhone. C, COX, A. Relative motions between oceanic and continental plates in the Pacific Basin. Geological Society of America, Special Paper , 54p. Zur stratigraphie und fauna des Lias zeta im nordwestlichen Deutschland.

Palaeontographica Stuttgart , V. Geological Survey of Canada, Memoir , p. Geological Survey of Canada, Bulletin 74, 43p. The Jurassic faunas of the Canadian Arctic - Cadoceratinae. Geological Survey of Canada, Bulletin , 27p. Geological Survey of Canada, Paper , 33p. Geological Survey of Canada, Bulletin 53, 47p.

Middle Callovian sedimentary rocks and guide ammonites from southwestern British Columbia. Geological Survey of Canada, Paper , 29p. Geologica Hungarica, Series Palaeontologica, V. HALL, R. Jurassic environments. Cambridge University Press, Cambridge. Eustatic cycles in the Jurassic. VON Liassic ammonite zones of South America and correlations with other provinces, with descriptions on new genera and species of ammonites, in Biostratigrafica de los sistemas regionales del Jurasico y Cretacico en America del Sur, Mendoza, pp.

Western Interior United States. On the Blake collection of ammonites from Kachh, India by L. F Spath Book 5 editions published in in English and held by 28 WorldCat member libraries worldwide. Additional observations on the invertebrates chiefly ammonites of the Jurassic and Cretaceous of East Greenland by L. F Spath Book 3 editions published in in English and held by 27 WorldCat member libraries worldwide.

The Eotriassic invertebrate fauna of east Greenland by L. On Bajocian ammonities and belemnites from eastern Persia Iran by L. F Spath Book 6 editions published in in English and held by 26 WorldCat member libraries worldwide. The Cephalopoda of the Neocomian belemnite beds of the Salt range by L. F Spath Book 7 editions published in in English and held by 25 WorldCat member libraries worldwide. Revision of the Jurassic cephalopod fauna of Kachh Cutch by L. F Spath Book 6 editions published in in English and held by 24 WorldCat member libraries worldwide.

The Jurassic and Cretaceous ammonites and belemnites of the Attock district by L. F Spath Book 4 editions published in in English and held by 23 WorldCat member libraries worldwide. The fossil fauna of the Samana range and some neighboring areas by Geological Survey of India Book 3 editions published in in English and held by 19 WorldCat member libraries worldwide.

F Spath Book 5 editions published in in English and held by 17 WorldCat member libraries worldwide. F Spath Book 6 editions published in in English and held by 14 WorldCat member libraries worldwide. Audience Level. Related Identities. Associated Subjects. Alternative Names. English German 1. Author , Creator. Q,