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This paper presents analyses of the measured peak side resistance of rock sockets constructed in weak claystone, shale, limestone, siltstone, and sandstone. The peak side resistance is obtained from in situ axial load tests on drilled shafts, anchors, and plugs. The parameters that affect the development of peak side resistance are determined using in situ load test data. It is found that peak side resistance increases with the unconfined compressive strength and deformation modulus of the weak rock, and decreases with the increase in length of the shear surface along the rock socket sidewalls. The increase in socket diameter also slightly decreases the peak side resistance. Additionally, it is found that the initial normal stresses do not significantly affect the measured peak side resistance in the in situ load tests. The in situ load test data are used to develop an empirical design equation for determination of the peak side resistance. The proposed model for peak side resistance and the reliability analysis are used to determine the corresponding resistance factors for use in the load and resistance factor design framework for assessment of the strength limit state.

The Upper Ordovician (mid-Katian) Kope Formation provides an example of how a detailed study of fine-grained siliciclastic sediment can provide sedimentological insights. The Kope Formation is an exemplar of mixed siliciclastic–carbonate cyclicity; however, most of the sedimentological research to date has focused on the fossiliferous limestone beds. Conversely, this paper provides a detailed investigation of siltstone within 42 metre-scale cycles from 26 locations spanning a large geographic area. The objective of the study is twofold: (i) to confirm the mineralogical nature of silt-sized sediment. Currently, silt-sized sediment is irregularly defined as being either carbonate or siliciclastic rich. This paper uses X-ray diffraction, thin-section, and elemental analyses to determine the mineralogy of the silt; (ii) to determine the stratigraphic distribution of siltstone beds. If a distinctive and reoccurring distribution of siltstone can be found, then it can provide additional information about environmental energy changes that led to cyclic fossiliferous limestone formation. This study finds that silt within the Kope Formation is siliciclastic and siltstone, therefore, records periodic minor pulses of coarser terrigenous sediment. Predominantly, metre-scale limestone–shale cycles show an increasing abundance of siltstone beds in the upper half of the shale interval, with a marked decrease just before the capping limestone. This finding supports the idea that limestone formation occurred during slowing sedimentation, perhaps at a time of maximum sea-level rise. Furthermore, decametre-scale fluctuations in siltstone abundance are similar in pattern to previously documented faunal variations, indicating that fauna assemblage might be more controlled by turbidity and not depth.

A very rare 11.2 m long wide-gauge trackway, made by an as yet undetermined large mammal, is described from the Lacombe Member (Late Paleocene) of the Paskapoo Formation (Paleocene). The exposure of the trackway was connected with the record-setting floods of 2013 in the province of Alberta as the tracks were exposed close to the base of the Brazeau Dam in west-central Alberta. The tracks are preserved on the top surface of a siltstone, but extensive erosion of the tracks resulted in the removal of details such as claw and digit traces, as well as any heel or palm impressions. The tracks are all circular to subcircular in outline, and it is not possible to determine the direction of travel of the trackmaker. Sequences of distinct pairings of adjacent tracks on both the left and right set of traces are present, and these are interpreted to represent manus-pes couples. The tracks do not show any overprinting. The mean pace angulations of the two best preserved sections range from 113° to 125°, while their mean stride lengths range from 95 to 96 cm. The lack of any distinctive anatomical details being preserved in the tracks prevents a precise identification of the trackmaker, but the sizes, shapes, and age of the tracks suggest that they could have been made by a large pantodont.

We describe the skull roof anatomy of PRPRC 2007.08.81, a new specimen of late Olenekian (Spathian) ichthyopterygian from the Vega-Phroso Siltstone Member of the Sulphur Mountain Formation of British Columbia, Canada. Based on the presence of a well-developed anterolateral prefrontal process, parietal that is deeply excavated along its posteromedial margin, and skull roof sutural patterns, PRPRC 2007.08.81 closely resembles other Olenekian forms such as Utatsusaurus, Grippia, Chaohusaurus, and Gulosaurus (a new taxon recently described from British Columbia, Canada). However, due to their shared apomorphic supratemporal terrace morphology, PRPRC 2007.08.81 is identified as Utatsusaurus sp. With the only other known conclusive Utatsusaurus material retrieved from the Osawa Formation (Lower Triassic) of Japan, the broad palaeogeographic distribution of this taxon suggests a radiation event for Ichthyopterygia occurring prior to the latter part of the Olenekian. However, despite this inference, the palaeogeographic origin of Ichthyopterygia continues to be unclear; only the acquisition and interpretation of additional chronologically early ichthyopterygian material will resolve the early evolutionary history of this group.

Strata of the Campbellton Formation, nearly 1 km-thick and known for its diverse fossil assemblage of early plants, arthropods, and fish, can be divided into six facies associations: (1) restricted lacustrine, (2) marginal lacustrine, (3) near-shore lacustrine, (4) coastal-deltaic, (5) sandy to gravelly alluvial plain, and (6) gravelly proximal alluvial environments. Lacustrine deposits with restricted circulation, due to depth or stagnation, are fine-grained with preserved organic material. The marginal lacustrine association consists of massive siltstone and very fine sandstone, interbedded with conglomerate. The latter are interpreted to have shed from older volcanic units forming the basin walls. The near-shore lacustrine association is characterized by rippled sandstone with microbialites. Alluvial strata include interbedded imbricate to nonimbricate conglomerate, trough cross-stratified sandstone, and barren to plant-bearing siltstone. Rare exposures of thickly bedded imbricate to weakly imbricated cobble–boulder conglomerate with sandy plant-bearing lenses are interpreted as products of hyperconcentrated debris flows. In the western belt, a braided-fluvial system had paleocurrents flowing WNW. Coastal-deltaic deposits west of the fluvial outcrops, containing aquatic vertebrates and invertebrates, had paleocurrents flowing ESE, suggesting a confined body of fresh or brackish water. In lower parts of the eastern belt, lacustrine facies are prevalent, representing a large open lake. Alluvial facies dominate upper parts of the formation, representing an eastward-flowing axial braided river system, with proximal alluvium shed transversely from the basin margins. Although most strata have a volcanic provenance, only one outcrop in the lacustrine beds shows evidence of active volcanism during deposition of the Campbellton Formation.

Dinosaur bones were discovered in 1971 during uranium exploration in the Sustut Basin, northern British Columbia, Canada. These bones have more recently been prepared and described and represent an indeterminate cerapodan dinosaur. Although dinosaur bones have been reported from British Columbia before now, this specimen represents their earliest recorded discovery from the province. The bones were collected from loose blocks in a talus slope, near the intersection of Birdflat Creek and the Sustut River. They are encased in hard siltstone that shares characteristics with adjacent outcrops of the Upper Cretaceous Brothers Peak Formation. Bones collected include the right humerus, right radius, the distal portion of the right tibia and fibula, two right pedal phalanges, including two unguals, and several unidentifiable fragments.

The eastern margin of the Kechika Graben in the vicinity of Muncho and Moose lakes, northeastern British Columbia, contains Middle Cambrian rift-related strata herein named the Mount Roosevelt Formation. The formation conformably overlies a quartzite package equivalent to the uppermost clastic unit of the informal late Early Cambrian Gataga group ( Bonnia – Olenellus zone) and is conformably overlain by a thick, unnamed carbonate sequence of Middle Cambrian age ( Plagiura – Poliella zone). The Mount Roosevelt Formation is subdivided into three members. The lowermost member is characterized by oöid-bearing siltstone and sandstone, interbedded with dolostone, limestone, and hematitic conglomerate. Conformably above this, the middle member is a thick sequence of polymict cobbly pebble conglomerate. The upper member includes karstified dolostone, calcareous-cemented conglomerate and sandstone, and limestone. Collectively the Mount Roosevelt Formation reflects alluvial fan delta progradation into a transgressive marine environment. Deposition occurred in an active fault-controlled basin, located on the eastern margin of the Kechika Graben adjacent to the Muskwa High. Basin initiation in the late Early Cambrian coincided with the reactivation of pre-existing regional faults. High rates of subsidence during the initial phase of extension were accommodated on these faults, which provided a locus for fan delta deposition. Continuing high rates of subsidence limited basinward fan delta development. Deposition of the formation ended with base-level transgression in the early Middle Cambrian that drowned the fan deltas and the adjacent Muskwa High and allowed development of the Kechika Trough above the older graben system.

Fossiliferous clasts occur in Carboniferous conglomerate in the Horton Group on western Isle Madame and in the Mabou Group on eastern Isle Madame. Most of the clasts (21 of 23 examined) are calcareous siltstone and sandstone that contain Silurian – Lower Devonian faunas comparable to those in the Arisaig area, northern mainland Nova Scotia, although the lithologies are coarser grained and less calcareous than those of the Arisaig section. These middle Paleozoic faunas are well constrained to the Silurian (uppermost Llandovery through Pridoli) and lowest Devonian and are characteristic of those known from shallow siliciclastic-dominated platforms of the Avalon microcontinent in Wales and England. The remaining two clasts have abundant inarticulate brachiopod shells that indicate provenance from Middle Cambrian proximal marine facies on the Avalonian marginal platform. No clasts were found that are likely to have been derived from the Torbrook Formation, and thus from the Meguma terrane in southwestern Nova Scotia, as has been previously reported. The association of relatively large, reworked fossiliferous clasts in Carboniferous conglomerate on Isle Madame suggests local derivation from lower and middle Paleozoic units not presently exposed, although probably present as subcrop under the Carboniferous units, in southwestern Cape Breton Island and adjacent mainland Nova Scotia.

40Ar/39Ar dates from eight muscovite separates and two whole-rock samples of slate, siltstone, and sandstone provide detrital, metamorphic, and post-metamorphic overprinting ages for the low-grade metamorphic rocks of the Meguma Supergroup in the Mahone Bay region of southern Nova Scotia. Variably reset detrital muscovite ages of 600-550 Ma agree with previously obtained U-Pb dates from detrital zircon. Separates of foliation-parallel muscovite yield precise 40Ar/39Ar ages of 395-388 Ma. Petrographic and metamorphic data indicate that these are metamorphic mica growth ages. The range overlaps with the younger limit of previously reported whole-rock ages (410-380 Ma), but is more tightly constrained. An apparent inconsistency between previous 40Ar/39Ar whole-rock ages as old as 410 Ma and regional deformation that affected sedimentary rocks as young as 385 Ma has been resolved by the younger ages reported here and by recent adjustments to the early Paleozoic time scale which suggest that the Lochkovian to Emsian Torbrook Group was deposited between 419 and 394 Ma. A muscovite plateau age of 376 Ma from one sample may be related to late-stage flexural slip deformation in the Ovens gold district.

The Brunswick No. 12 massive sulphide deposit occurs within a Middle Ordovician bimodal volcanic and sedimentary sequence that is thought to have formed in a continental back-arc rift covered with a thick succession of carbonaceous hemipelagic and turbiditic sedimentary rocks. The deposit consists of three en echelon lenses that are zoned from Vent Complex to Bedded Ore and Bedded pyrite facies. The Bedded Ore facies has the lowest average δ34S values (14.2[Formula: see text]), but are only slightly less positive than laminated pyrite in footwall sedimentary rocks (δ34Smean = 15.1[Formula: see text]). δ34S values for the bedded sulphides show an upward increase from 14.2[Formula: see text] in Bedded Ore to 16.5[Formula: see text] in Bedded Pyrite. Average δ34S values for Vent Complex (15.8[Formula: see text]) and underlying stringer sulphides (16.1[Formula: see text]) are consistently more positive than those for Bedded Ore. In carbonaceous shales and siltstone of the Patrick Brook Formation that underlie the deposit, δ34S values that range between 13.8 and 25.6[Formula: see text], and the similarity of these values to those of the Brunswick No. 12 deposit indicate major bacterial reduction of sulphate to sulphide under closed or partly closed conditions, and that most of the S in the deposit originated from ambient sulphidic bottom waters. Furthermore, the average δ34S value for Brunswick No. 12 bedded ores lies on the Selwyn Basin pyrite evolutionary curve and indicates that anoxic conditions within the Tetagouche back-arc basin reflect a global anoxic episode. The Brunswick No. 12 deposit probably formed, therefore, by the mixing of hydrothermal metals with dissolved sulphide of seawater origin during periods of ocean anoxia. The increase of δ34S values towards the Vent Complex may reflect the addition of isotopically heavy S formed by the inorganic reduction of seawater sulphate.

The Caledonian Highlands of southern New Brunswick consist of Late Proterozoic to Cambrian rocks generally considered typical of the Avalon terrane of the northern Appalachian Orogen. Mainly tuffaceous volcanic and sedimentary rocks of the Broad River Group and cogenetic dioritic to granitic plutons with ages ca. 620 Ma form most of the eastern Caledonian Highlands. They have petrological features indicative of origin in a continental margin subduction zone. Significantly younger ca. 560–550 Ma dacitic to rhyolitic lapilli tuffs and flows, laminated tuffaceous siltstone, basaltic and rhyolitic flows, and clastic sedimentary rocks of the Coldbrook Group form most of the western highlands, and occur locally throughout the highlands. The mainly tuffaceous lower part of the group has been intruded by gabbroic and syenogranitic plutons that are interpreted to be cogenetic with basaltic and rhyolitic flows in the upper part of the group. This voluminous subaerial magmatism may have formed during postorogenic extension in the earlier ca. 620 Ma subduction zone complex represented by the Broad River Group and associated plutons. This tectono-magmatic model differs from other interpretations that related most of the igneous units to ca. 630–600 Ma subduction, and did not recognize the importance of ca. 560–550 Ma magmatism. The ca 620 Ma subduction-related volcanic and plutonic rocks of the Caledonian Highlands are comparable to units in other parts of the Avalon terrane, but voluminous ca. 560–550 Ma igneous activity like that represented by the Coldbrook Group and related plutons has not been documented yet in other Avalonian areas.

Fragments of siltstone were subjected to the slake durability test. The profiles of the rock fragments experienced changes during the test as a result of saturation and abrasion-induced stresses. The profiles of the fragments were evaluated before and after the test using fractal analysis. Fractal analysis uses the concept of fractal dimension to calculate the roughness of profiles. Before the test, the profiles of the siltstone particles had an average fractal dimension equal to 1.1364. After the test, the average fractal dimension of the profiles became equal to 1.1187. The change in fractal dimension was a reflection of the smoothing action on the particle profiles by the combined effects of abrasion and wetting and drying action that take place during the slake durability test. Key words : durability, shape of rock fragments, fractal dimension.

The Lower – lower Middle Ordovician Beekmantown Group of the St. Lawrence Lowlands is a variably thick pertitidal succession of dolostone, limestone, quartzose carbonate, and subordinate siltstone and shale that is gradationally bound by the Potsdam Group below and unconformably to conformably by the Chazy Group above. It is here considered to include three regionally extensive formations, a basal Theresa, a middle Beauharnois, and an upper, redefined Carillon. A principal reference section is established in the subsurface. The Theresa Formation is a transgressive succession, above Potsdam Group siliciclastics and below Beauharnois Formation carbonates. It is dominated by quartz arenite and quartzose dolostone; skeletal fossils are rare (usually gastropods), whereas trace fossils are abundant. The Beauharnois Formation is divided into two members, a basal Ogdensburg and an upper Huntingdon. The Ogdensburg Member is sandy, especially in its lower part, and relatively more fossiliferous than the Huntingdon Member. Both members include fossiliferous and nonfossiliferous, stromatolitic and oolitic, coarse-grained dolostone and subordinate limestone and reflect the development of a relatively wide peritidal carbonate platform. The Carillon Formation is a widespread unit that marks the onset of Middle Ordovician Taconic orogeny at the continental margin. It consists mostly of cyclic packages of laminated and burrowed, fine-grained dolostone and limestone, and as well siltstone and shale. Thin fossiliferous beds are dispersed in its upper part.

Several lower Mesozoic, fault-bounded units separate the Intermontane and Insular superterranes in southwestern British Columbia. Detailed study of one of these Mesozoic units, the Cadwallader Group, helps clarify the boundary between the superterranes and establish the tectonic evolution of southwestern British Columbia. The Cadwallader Group is the oldest unit in an Upper Triassic through Middle Jurassic volcanic and sedimentary tectono-stratigraphic terrane. Two formations, the Pioneer and the Hurley, compose the Cadwallader Group; the previously recognized Noel Formation is no longer considered valid. The Pioneer Formation contains pillow basalt, flows, and basalt breccia. Siltstone, sandstone, conglomerate, and minor amounts of limestone megabreccia and basalt belonging to the Hurley Formation conformably overlie the Pioneer. The Hurley spans latest Carnian or earliest Norian to middle Norian time. Two episodes of deformation affected the Cadwallader, and a thrust fault separates the group from slightly younger clastic rocks of the Tyaughton Group. Similarities in clastic rocks indicate the Tyaughton was deposited on the Cadwallader; together the units form the Cadwallader terrane. Basalts and clastic rocks in the terrane record deposition in or near a Carnian to earliest Norian volcanic arc. Volcanism waned later in the Norian, but presence of the arc is preserved in the clastic rocks.Oceanic rocks of the Middle Triassic to Middle Jurassic Bridge River terrane became juxtaposed with the Cadwallader terrane in Middle Jurassic time, after which the terranes functioned as a single tectonic block. Contrasting volcanic histories suggest that the Cadwallader terrane was not accreted to the Intermontane superterrane until Middle Jurassic or Early Cretaceous time, although the similar tectonic settings of Stikinia and the Cadwallader terrane allow a common earlier history. The Cadwallader terrane is not part of either the Alexander terrane or Wrangellia, and so the inboard margin of the Insular superterrane must lie west of the Cadwallader terrane.

Braided river, sheetflood, and playa lake sediments of the Tynemouth Creek Formation (Lower Pennsylvanian) show superficial synsedimentary faulting and subsurface post-depositional sediment remobilization. A prominent palaeosol has been offset 90 cm on two faults, movement on which clearly preceded deposition of the overlying beds. Seventeen to 25 m below this horizon, large load structures, upward-branching siltstone intrusions, and three types of sandstone dike are recognised. Intrusion occurred on several occasions at different depths of burial and was the result of rapid, probably earthquake-induced dewatering. This interpretation is supported by the location of the study area, only a few kilometres to the north of the Cobequid–Chedabucto Fault, on which major strike-slip movement occurred during the Pennsylvanian.

Spieden and Sentinel Islands, San Juan Islands, Washington, are underlain by the only known occurrence of the Spieden Group, composed of the Upper Jurassic (Oxfordian or Kimmeridgian) Spieden Bluff Formation and the Lower Cretaceous (Valanginian and Hauterivian and possibly younger) Sentinel Island Formation, separated by a disconformity.The 100 m thick Spieden Bluff Formation is subdivided into two members: (1) an 80 m thick lower member, consisting of 5 m of sandstone, siltstone, and tuff overlain by 75 m of volcanic breccia–conglomerate largely of debris flow (laharic?) origin; and (2) a 20 m thick upper member consisting of fossiliferous sandstone and siltstone deposited on a shallow marine slope. Sedimentologic, petrologic, and geochronologic data suggest that sediments of the Spieden Bluff Formation accumulated near an active volcanic source to the north contributing primarily andesite, dacite, and basaltic andesite.The 740 m thick Sentinel Island Formation is also subdivided into two members: (1) a 140 m thick lower member consisting of fossiliferous sandstone and siltstone deposited in a shallow marine environment; and (2) an unconformably overlying 600 m thick upper member consisting of volcanic conglomerate deposited as an alluvial fan. The source terrane for the Sentinel Island Formation was also primarily Upper Jurassic volcanic rocks and lay to the northeast.Rocks of equivalent age occur in the southern part of the San Juan Islands and in neighboring geologic provinces, but most of these correlative rocks differ from the Spieden in sedimentology, structural style, and metamorphism. Juxtaposition of the Spieden Group and these correlative rocks might have been accomplished by shortening and fragmentation of a regional convergent margin, by large-scale transport of allochthonous blocks, or by some combination of the two mechanisms.

Shallow marine deposits of the Arisaig Group (Silurian–Devonian) of Nova Scotia consist of shaly sediments with varying proportions of coarser interbeds. Brachiopods, graptolites, crinoids, corals, and bivalves are present in parts of the group.One end-member lithology consists of black, fissile shale with few fossils. This grades into grayer, less fissile, more fossiliferous shale with coarse siltstone interbeds up to 5 cm thick. Higher in the group, nearer nonmarine beds, the background sediments consist of mottled, nonfissile silty mudstone with many large in situ brachiopods and lenses of coarse siltstone. The interbeds are composed of coarse siltstone or fine sandstone and, in some cases, have lenses of coquina within them. They range from 5–50 cm in thickness, but in places have amalgamated by scouring and locally comprise almost 100% of the section. Most of the coarse interbeds have sharp bases with horizontal or low angle laminations, but some thicker beds show sets of low angle, curving laminations which truncate other sets, termed “hummocky cross-stratification," The top surfaces of these beds are covered by interference ripples and burrows.The coarse interbeds were laid down rapidly by fractional seaward-flowing bottom currents during storms. Some of the coarse beds were later modified by bioturbation during fair weather periods when settling of sediment from suspension and faunal activity were the dominant processes. The Arisaig Group represents the deposits of a storm-dominated shelf and illustrates the range in variation which can occur in the sediments of this type of environment.

Conventional methods of piezometer response testing are unsuitable for analyzing observed data from three piezometers placed in fractured coal and siltstone units. However, these responses correspond closely to the results of pressure tests in fractured limestones (Pollard). Following an extended form of the Pollard analysis, the fracture porosity within fractured coal units is calculated to comprise approximately 3.7% of the total porosity. In the deeper siltstone unit, the fracture porosity makes up only 0.5% of the total porosity. The application of basic time lag principles (Hvorslev) to separate segments of the Pollard plot makes it possible to determine the hydraulic conductivity of the matrix and fracture systems. The hydraulic conductivity of the fracture system is calculated to be 40 to 250 times higher than the matrix.

The Double Mer Formation is a sequence of redbed arkosic sandstone, conglomerate, siltstone, and shale in the Grenville Province of eastern Labrador. The formation is closely associated with a rift system extending inland for at least 300 km from the Labrador coast. Substantial thicknesses of strata of Double Mer Formation are confined to two basins, the Lake Melville graben and the Double Mer half graben. Strata correlated with the Double Mer Formation are found elsewhere in southeast Labrador; one isolated outcrop occurs within the Sandwich Bay graben, a separate, smaller basin 100 km to the southeast that trends parallel to the Lake Melville graben.The only definite age constraint on the Double Mer Formation is that it postdates Grenvillian deformation. Previously, the formation was assigned a latest Precambrian to Early Cambrian age based on lithological similarity with the Lower Cambrian Bradore Formation of the southeast coast of Labrador. On the basis of a structural model proposed here that suggests a link between graben configuration and latest Precambrian – Early Cambrian mafic dike trends, we concur with this viewpoint. The Double Mer Formation thus preserves the basin fill presumed to have accompanied graben formation, which, together with emplacement of mafic dikes and anorogenic plutons, documents latest Precambrian to Early Cambrian crustal extension that eventually led to the opening of the Iapetus Ocean.

Analyses of seismic reflection profiles supported by lithological and palynological studies of core samples from submarine outcrops indicate that the lower Paleozoic succession of the Avalon Terrane, southeast Newfoundland, is continuous offshore. The succession crops out over an area greater than 30 000 km2 and is approximately 8 km thick. The sequence is dominantly siltstone and is of Late Cambrian to ?Devonian or younger age. It is relatively unmetamorphosed, underlain by Hadrynian acoustic basement, and overlain along its eastern and southern margins by a Mesozoic–Cenozoic succession that is economically important from an oil and gas perspective.Lithofacies studies indicate that in Early Ordovician time restricted shallow-marine conditions probably prevailed over a vast area of the Avalon Terrane. Upper Ordovician and Silurian siltstones show evidence of deposition under more-dynamic and well-oxygenated conditions and probably represent a normal shallow-marine environment. Redbeds of possible Devonian or younger age are interpreted to be of continental origin. Black shales of Ordovician age are potential source rocks for the generation of hydrocarbons.

Six lithologic units, including two newly named formations, were mapped on Randall, Dunira, and nearby islands. The islands are characterized by greenschist-facies metamorphism and westerly directed thrusting. The oldest unit is a Late Mississippian, massive limestone on Ducie Island. The Dunira Formation, composed of thin-bedded limestone and siltstone, is Early and Middle Pennsylvanian in age. It is unconformably overlain by limestone and dolomite of the Upper Triassic Randall Formation. The Randall Formation grades upwards into a green phyllitic unit of Late Triassic(?) age. Rhyolitic and more mafic volcanic rocks may represent a bimodal volcanic suite of Early Jurassic age, based on a U–Pb date of 188 Ma on zircons. These five units correlate with rocks in the Alexander Terrane in southeastern Alaska. The sixth and presumed youngest unit consists of flysch-like sedimentary rocks of probable Middle Jurassic to Early Cretaceous age that may correlate with rocks of the Gravina–Nutzotin belt. The three older units yielded 15 conodont genera from 29 localities. The 13 Paleozoic genera are described and illustrated.

The Carmanville ophiolitic mélange of northeastern Newfoundland forms an olistostrome within a thick succession of Middle to Upper Ordovician flyschoid shale, siltstone, and grey-wacke. The olistostrome consists of sedimentary, volcanic, and ultramafic olistoliths ranging in size from granules to several kilometres. The matrix appears to have been derived entirely by disaggregation and disintegration of hydroplastic and thixotropic sediments. The matrix was sufficiently fluid for turbulent motion to occur in the lower parts of the olistostrome, yet viscous enough to produce alignment of fragments and a pervasive cleavage, as well as drag folds in the surrounding hydroplastic sediments. The olistoliths have been drawn from a stratigraphic column hundreds, if not thousands, of metres thick, and an area many kilometres across. A small proportion of the olistoliths were deformed and metamorphosed prior to incorporation in the olistostrome.The Carmanville ophiolitic mélange is tentatively correlated with the Dunnage mélange to define the northern margin of a sheet of ocean floor and island arc obducted toward the southeast onto an accreting continental rise in Llanvirnian–Llandeilian time. Olistostrome formation within this unstable pile commenced in post-Arenigian time, and may have continued intermittently until Llandoverian time. The olistostrome and surrounding rocks were further deformed, metamorphosed, and intruded by granitoid plutons during Silurian and Devonian time.

The Somerset Island Formation of Somerset Island is a newly defined unit consisting of interbedded fine-grained, grey, planar-laminated dolomite and limestone, grey mottled limestone and dolomite, red quartzose siltstone and red dolosiltite. It forms a transitional unit between the limestone and dolomite of the underlying Read Bay Formation and the sandstone and conglomerate of the overlying Peel Sound Formation, and ranges in thickness from 150 to more than 400 m. The formation was formed predominantly in intertidal and supratidal environments and forms the lowest part of a regressive sequence that culminates in boulder conglomerates of alluvial fan origin in the Peel Sound Formation. The Somerset Island Formation is predominantly Pridolian in age, but may include some strata of Ludlovian and Gedinnian age.The regressive sequence reflects a major pulse of the Cornwallis Disturbance of Boothia Uplift. A similar sequence occurs in Prince of Wales Island, although the lower part of the succession there contains conglomerate and sandstone, rock types that are absent in Somerset Island. These rocks are formally assigned to the Lower Peel Sound Formation but are of similar age to the Somerset Island Formation of the type area.Rocks of similar facies to the Somerset Island Formation of Somerset Island comprise the upper member of the Drake Bay Formation on Russell Island and Member D of the Read Bay Formation on Cornwallis Island. The latter unit is younger than the Somerset Island Formation, reflecting a later commencement of regression in that area.

Cleavage is sporadically developed in Late Triassic redbeds of the Lepreau Formation in folds and in areas of uniform northwestward dip in the lower Lepreau River – Lepreau Harbour half-graben. The cleavage in shaly siltstone beds is a composite incipient fabric defined by patchily developed crenulated bedding laminae, pressure solution planes, and mineral orientation parallel to the cleavage direction; cleavage in sandstone beds is defined by alignment of submicroscopic cracks inferred from laboratory tests. The cleavage fabrics are subvertical trending northeast–southwest, and resulted from horizontal northwest–southeast compression. Closely spaced fractures subparallel to the cleavage fabric in both shaly siltstones and sandstones are interpreted as later structures formed during relaxation of tectonic stresses. The cleavage fabrics and fractures are also present in intraformational clasts of shaly siltstone and rare sandstone clasts within conglomerate beds. A distinct shape orientation of the shaly siltstone clasts parallel to their cleavage within relatively undeformed conglomerate is attributed to compression during folding of unconsolidated conglomerate beds. The mean cleavage orientation varies from coplanar to noncoplanar with fold axial surfaces. The folds and cleavage formed during lateral compression probably related to wrench faulting which postdates the formation of the Triassic grabens.

Blocks of limestone and dolomite up to tens of metres across occur near the base of the Lower Devonian (Siegenian–Emsian) Stuart Bay Formation at six sites on eastern Bathurst Island. These blocks occur in groups of up to 30. At the two localities with the greatest number of blocks they are disposed in two or three roughly linear groups reflecting their occurrence on bedding planes. The blocks are mostly wackestones and floatstones and they contain abundant fossils of the reefal biofacies of which stromatoporoids and corals are most prominent.The blocks have weathered from a matrix of finely laminated deep-water siltstone. Most of the blocks are unbedded but where bedding attitudes can be measured they are discordant with that of the siltstone and those of neighbouring blocks. Although they have been described as bioherms that grew in place, the evidence indicates that they are allochthonous blocks derived when several catastrophic events such as earthquakes disturbed a Devonian reef tract developed on the western flank of the Cornwallis Fold Belt.

Resedimented deposits in the Ordovician Cap des Rosiers Formation near Grosses Roches, Quebec, are arranged in fining-upwards sequences, each with conglomerate at the base, and argillaceous sandstones, or interbedded sandstones and shales at the top. The conglomerates are primarily cobble-grade, and are poorly sorted; graded bedding and clast imbrication are poorly developed, and internal stratification is uncommon. They pass upwards and laterally to pebbly sandstones and sandstones, most of which are massive, but which contain cross-stratification, parallel stratification, or dish structure in places. The sandstones are overlain by finer-grained sandstones with many load-deformation and water-escape structures and at the top of some sequences there are sandstone and siltstone turbidites. The presence of large sediment slabs and soft clasts in the conglomerates and sandstones, and of the abundant shale chips in the argillaceous sandstones, provides evidence of penecontemporaneous erosion. Load casts, flame structures, dish structures, and other water-escape structures indicate relatively high rates of deposition. At the base of the section, 10–12 m of conglomerate and sandstone beds in the lowermost sequence onlap against the eroded pelites of a channel margin. The exposed bases of four other fining-upwards sequences are erosional, but no onlapping relationships are observable, and the eroded sediments are coarser grained than the pelites at the very base of the section.The sequences are considered to represent the back-filling of a channel-mouth in the mid-fan region of a submarine fan, and subsequent accumulation of fining-upwards lobes beyond the front of a principal channel which continued to supply sediment. The superposition of conglomerate-bearing fining-upwards sequences is interpreted as a result of fluctuations in supply from a tectonically active source.

Overlying the Keweenawan lavas of northern Wisconsin and Michigan is a thick sequence of terrestrial sandstone, shale, and siltstone that has undergone some tectonic deformation associated with movement along thrust faults and the development of the Lake Superior syncline. Thermal and alternating field demagnetization, chemical leaching, and multivector analysis using orthogonal projections reveal a trivector structure of the natural remanent magnetization (NRM) of the Fond du Lac Formation and Middle River section (Amnicon and Orienta Formations), and a bivector structure of the NRM of the Eileen section (Eileen Formation). The components may be classified by their physical properties as revealed by demagnetization. A population of high blocking temperature components, K1, is found in all three sections and gives poles as follows: Fond du Lac, 16°N, 160°E; Middle River, 25°N, 148°E; Eileen, 20°N, 156°E after structural correction is applied. A population of intermediate blocking temperature components, K2, is post-tectonic and found only in the Fond du Lac Formation and Middle River section. Poles calculated from K2 fall among the Grenville type poles (Fond du Lac, 9°S, 145°E; Middle River, 24°S, 162°E). A third population of components, K3, has low blocking temperature and coercivity and is isolated only by chemical leaching. K3 has steep positive inclination, northern declination, and is post-tectonic. It is interpreted as a recent magnetization.Any interpretation of the path of apparent polar wander for North America must accommodate the sequence of magnetization K1 to K2. The timing of tectonism in the Keweenawan basin is bracketed by the times of acquisition of K1 and K2. These results reconfirm some recent interpretations that include Grenville poles on the polar wander track of interior Laurentia.

The heavy minerals found in diamictites and intrastratal sandstone and siltstone rhythmites of the Late Precambrian Gaskiers Formation of Newfoundland are dominated by altered pyroxenes and amphiboles with lesser amounts of garnet and zircon and trace amounts of tourmaline and rutile. The garnets are angular, fresh in appearance, and about 9% of the garnets have glacially derived chattermark trails. This observation, along with the presence of striated and facetted clasts, suggest that at some time prior to final deposition, the diamictites underwent transport in glaciers which were of ice cap or ice sheet dimensions.

The Snyder Group is an Aphebian sedimentary sequence unconformably overlying Archean rocks that has undergone deformation and a medium to high grade contact metamorphism as the result of the emplacement of the Elsonian Kiglapait intrusion. Five lithostratigraphic units totaling 239 m in thickness have been recognized; in ascending order they are: (1) a lower quartz arenite with local arkosic arenites, pelites, conglomerates and a discontinuous basal conglomerate; (2) a manganiferous silicate iron formation; (3) a marble with associated calc-silicates and quartzites; (4) a sphalerite- and pyrrhotite-bearing quartz-rich, graphitic siltstone; and (5) an upper quartzite. The several intrusive rocks are largely basic and intermediate in composition and are grouped as being emplaced either before or after the contact metamorphism by the Kiglapait intrusion. Collectively, their sills and dikes have expanded the section to 355 m.The lower and upper quartzites with their high maturity; poly modal festoon, trough crossbedding; reactivation surfaces; flaser and lenticular bedding; ripple marks; graded bedding; and conglomerates were probably deposited on a shallow, subtidal, tide- and current-dominated sand flat dissected by tidal channels. The few metapelites record deposition during an occasional less turbulent environment. The fine grain size, intraformational conglomerates, cross-laminations, and thin laminations of the intermediate formations indicate that they were deposited in a quiet, probably shallow water environment disturbed only by occasional storms. The sedimentary structures, lithologies and thin, sheet geometries of the beds suggest that the Snyder Group represents a siliciclastic sea shelf sedimentation, which, if reconstructions of the North Atlantic craton are correct, was epicontinental.

The Upper Cambrian? – Arenigian succession of Bell, Little Bell, and Kellys islands, Conception Bay, eastern Newfoundland, consists of at least 1500 m of interbedded micaceous sandstones, siltstones, shales, and ironstones. The succession has previously been formally subdivided into only two groups, namely, a lowermost Bell Island Group and an overlying Wabana Group. The existing lithostratigraphic nomenclature below group level has, to date, only been informally proposed and is therefore herein formally revised. The lowermost Bell Island Group comprises from base to top the Kellys Island, Little Bell Island, Beach, Redmans, Ochre Cove, and Dominion formations. Of these, the Ochre Cove and Dominion formations are newly proposed and the Beach Formation is considerably revised from its historical usage. The Beach Formation contains two newly proposed members, the McGraw and Eastern Head members, both of which in previous nomenclature were informally referred to as "beds." The disconformably overlying Wabana Group comprises from base to top the Powers Steps, Scotia, Grebes Nest Point, Gull Island, and Gravel Head formations. Of these, the Gravel Head Formation is revised from its historical usage and the remainder are newly proposed. The Powers Steps Formation contains a newly proposed member, the Youngsters Gulch Member, previously in part referred to informally as the "pyrite bed."

The Llandovery siliciclastic Ross Brook Formation of Arisaig, Nova Scotia, comprises three broadly defined sedimentary facies. These are a mottled silty mudstone facies (facies A), a laminated shale facies (facies B), and a laminated siltstone facies (facies C). Facies A consists of variably bioturbated silty mudstones, muddy siltstones, and fissile shales. It developed in relatively shallow water conditions; mudstones were presumably deposited from suspension, and siltstone laminae and thin layers were formed by increased wave and current activity. Mottling resulted from bioturbation by epifaunal and, particularly, infaunal benthic organisms. Within facies A, two subfacies are recognized: A(i) is mudstone dominated, and A(ii) is fine-grained siltstone dominated. Facies B consists of alternating laminae of undisturbed mudstone and fine-grained siltstone probably produced as a result of deposition from suspension during a temporary upward expansion of the oxygen-minimum layer. Facies C consists of 0.5–30 cm thick fine- to coarse-grained siltstones, which occur in lenses or layers of single, composite, or amalgamated units. Internally they are extremely variable, but all are interpreted as a result of deposition from storm-generated currents.The Ross Brook Formation formed on a shallow-marine, storm-influenced, subtidal inner–mid muddy shelf and is dominated by extensive but stratigraphically variable developments of facies A and facies C. Absolute water depth per se is difficult to assess, and although fluctuations occurred, much of the sequence is believed to have accumulated at or in the immediate vicinity of fair-weather wave base in water depths estimated to have been between 30 and 60 m. Silt supply was generally low, possibly reflecting great distance from source or the presence of a mud-dominated shoreline.Five brachiopod-dominated associations, which are stratigraphically the Eocoelia hemisphaerica, the Eocoelia intermedia – Eocoelia curtisi, the Visbyella nana, the "Camarotoechia" rossonia, and the Eocoelia sulcata associations, occur through the sequence. Associations change where die sum of the facies characteristics change, suggesting that the major physical controlling factor was substrate type and related environmental parameters. The development of discrete but intergrading associations is viewed as a consequence of the long-term persistence of a set of conservative animal–sediment relationships, superimposed on which is the evolutionary pattern of immigration and extinction of individual species.

The late Precambrian Coldbrook volcanic sequence and stratigraphic equivalents in southern New Brunswick can be divided into three distinct belts. These have been named the Eastern, Central and Western Volcanic Belts.The Eastern Volcanic Belt, along the Bay of Fundy coast, is characterized by intensely deformed mafic and felsic flows, tuffs, and abundant related volcanogenic sediments. Two thick arkosic sedimentary units in this belt reflect extensive intervals of volcanic quiescence. Fine-grained siliceous siltstone and conglomerate, locally intercalated with these rocks, have probably been derived from erosion of older Precambrian basement rocks to the northwest.The Central Volcanic Belt is composed of generally weakly deformed felsic and lesser mafic flows, and coarse lithic tuffs (including ignimbrites), and very minor intercalated sediments. The almost complete lack of water-lain sediments and presence of ignimbrites suggests subaerial deposition for most of these volcanic rocks. The relationship between rocks of the Central and Eastern Volcanic Belts is one of facies equivalence. The Western Volcanic Belt is also composed of felsic and minor mafic flows and tuffs that resemble those of the Central Volcanic Belt, but they are intensely deformed. Minor volcanogenic sedimentary rocks are intercalated with the volcanic rocks along the northwestern margin of this belt.The nature and distribution of major lithofacies belts in the Coldbrook Group and stratigraphic equivalents appear to be consistent with deposition along the margin of an intracratonic basin. It is possible, however, that further work may prove an ensialic island arc model to be a viable alternative.

Contemporaneous faults and clastic intrusions near Elliot Lake are common within the Espanola Formation of the Quirke Lake Group. Contemporaneous faults formed in response to differential vertical displacements which controlled regional paleocurrents and basin slope. The normal faults within the sedimentary succession probably channeled the intrusive material of the clastic dikes. Four types of clastic dikes occur in the Espanola Formation: internally sorted conglomerate dikes; internally unsorted conglomerate dikes; thin sand- and siltstone dikes; and discordant sandstone masses with scattered quartz pebbles. Emplacement of the conglomerate masses into the Espanola Formation may represent a sub-permafrost phenomenon, provided the glacial origin for the boulder conglomerates within the Huronian succession is accepted.

The Meguma group of lithic greywacke, feldspathic quartzite, slate siltstone, and argillite is Early Ordovician or older in age and has undergone both regional and contact metamorphism. Both types of metamorphism have resulted in recrystallization and locally in orientation of newly formed minerals. Metasomatism and retrogressive metamorphism are subordinate and only locally important. Regionally metamorphosed rocks are divided into greenschist and almandine–amphibolite facies, although some assemblages cannot be assigned with certainty. Locally, biotite and garnet isograds are mappable within the greenschist zone.Relationships between regional metamorphism and structural elements (folding) show that deformation preceded regional metamorphism. Intrusion of granitic rocks has produced a zone of contact metamorphism (hornblende–hornfels facies) that is superimposed upon regional greenschist facies rocks, which shows that granite emplacement occurred after the regional grade was reached. Gold–quartz veins are confined to areas lying in the greenschist zone of regional metamorphism, which suggests that the almandine–amphibolite zone is not favorable.

Roof pendants of a late Aphebian (~1800 m.y.) volcano–sedimentary complex, within Hudsonian granites, outcrop on the eastern shore of Great Bear Lake. The volcano–sedimentary complex is similar to, and may be correlated with, the Echo Bay Group which outcrops farther to the north.The volcanic rocks are interbedded with immature volcanoclastic sedimentary rocks and with thinner units of calcargillite and dolomite. A unit of conglomerate, tuff, and siltstone, previously correlated with the Cameron Bay Group, is assigned to the 'Balachey Unit', until its relationships with other groups in the area are more clearly understood.Hudsonian granitic stocks and batholiths (~ 1750 m.y.) intruded the complex. Sharp contacts and narrow aureoles characterize these as high level intrusions. Zones of sulfide replacement are common in the aureoles. Porphyry dikes and stocks of similar age to the granites and rare, pegmatitic magnetite–apatite–actinolite bodies, also intrude the volcano–sedimentary complex.Three sets of diabase intrusions are identified, and related to three distinct fault directions. Giant quartz veins and mineralization of the U–Ag–Ni, Co arsenide – Bi type are found in zones of northeast-striking dextral faults.The volcano–sedimentary complex is interpreted as the molasse phase of the rising orogen of the Coronation Geosyncline, and is related to earlier deposits (the Snare and Epworth Groups) closer to the craton in the eastern part of the geosyncline.

An outlier of sedimentary rock assigned to the Gowganda Formation of the Huronian Supergroup was discovered during field mapping in the Goulais River area, District of Algoma, Ontario. This outlier is the northernmost documented occurrence of Huronian sedimentary rocks in the Algoma region. The outlier is 53 m in stratigraphic thickness and consists of polymictic to oligomictic paraconglomerate and orthoconglomerate with interbeds of pink arkose, siltstone, and dark grey greywacke. The conglomerates contain metavolcanic fragments and altered feldspars that suggest part of the sediment had a nearby source. Hematite results in a pink matrix in both conglomerates and arkosic interbeds and may indicate that an oxidizing environment prevailed during deposition. Air photo interpretation may help locate other outliers in the vicinity of lineaments, faults, or topographic highs.