Depositional environments of a thick Proterozoic sandstone: the (Huronian) Mississagi Formation of Ontario, Canada

1978 ◽  
Vol 15 (2) ◽  
pp. 190-206 ◽  
Author(s):  
Darrel G. F. Long
Keyword(s):  
Depositional Environments ◽  
Stratified Medium ◽  
River Systems ◽  
North Shore ◽  
The North ◽  
Lake Region ◽  
Braided Stream ◽  
Major River ◽  
Flowing System ◽  
Mixed Load

The Mississagi Formation is a thick (up to 3.4 km) Proterozoic arenite sequence that forms part of the Huronian (lower Aphebian [Formula: see text]) succession of the north shore of Lake Huron, Ontario. The formation is characterized by planar and to a lesser extent trough cross-stratified medium to coarse feldspathic arenites, with only minor amounts of argillite and conglomerate. Although the formation lacks any regular systematic cyclicity, both thinning upward and fining upward sequences can be recognized in some sections. Paleocurrent roses for individual outcrops are typically unimodal, although some bimodal distributions are recognized. The bulk of the formation is interpreted to be the result of deposition in a fluvial environment, principally from bed load and mixed load streams. These rivers were probably marked by a braided stream pattern in which channels were characterized by intermediate to low sinuosities and high width to depth ratios. Regional paleocurrent and petrographic trends indicate that two major river systems were operative. One system flowed east and south from the Sault Ste. Marie – Elliot Lake region to meet a second, southwesterly flowing system originating in the Cobalt Plain. These systems met in the southern Huronian area, from where the coalescing river systems flowed south.

Alluvial–playa sedimentation in the lower Keweenawan Sibley Group, Thunder Bay District, Ontario

1986 ◽  
Vol 23 (4) ◽  
pp. 527-542 ◽  
Author(s):  
Burns A. Cheadle
Keyword(s):  
Depositional Environments ◽  
Midcontinent Rift ◽  
North Shore ◽  
The North ◽  
Thunder Bay ◽  
Lake Formation ◽  
Playa Lake ◽  
Main Period ◽  
Sand Flats ◽  
Middle Proterozoic

The Middle Proterozoic Sibley Group is a mixed clastic–carbonate red bed sequence located in the Thunder Bay – Nipigon area on the north shore of Lake Superior. The lowest unit, the Pass Lake Formation, consists of a basal paraconglomerate member, of probable alluvial debris-flow origin, overlain by 20–80 m of plane-bedded and cross-bedded quartz arenites, which were probably deposited by sheetfloods and eolian processes on alluvial outwash sand flats. The overlying Rossport Formation is dominated by red and buff dolomicritic mudstone. The association of these mudstones with relatively pure massive carbonate beds and sheetflood sandstone units is strongly suggestive of a playa lake depositional environment. Fluctuations in playa lake levels may have resulted in oscillations between carbonate-dominated and clastic-dominated sedimentation. The upper unit, the Kama Hill Formation, consists of horizontally laminated purple shales and ripple cross-laminated buff siltstones to fine sandstones. The presence of stacked "powering-down" sequences and abundant dessiccation features is suggestive of sheetflood deposition on a distal alluvial floodplain.The sequence of depositional environments suggests that the Sibley Basin formed by stretching and sagging of the Middle Proterozoic crust preceding the main period of volcanic activity along the Keweenawan Midcontinent Rift Zone. In this sense, the Sibley Group red beds represent the earliest products of Keweenawan rifting. They were not, however, deposited in a classical aulacogen or "failed arm."

On Riccia marginata and related species (Ricciaceae, Marchantiophyta)

2012 ◽  
Vol 46 ◽  
pp. 298-305 ◽  
Author(s):  
A. D. Potemkin ◽  
T. Ahti
Keyword(s):  
Related Species ◽  
Lake Ladoga ◽  
Leningrad Region ◽  
Sem Images ◽  
North Shore ◽  
The North ◽  
Molecular Studies ◽  
The Future ◽  
The Town

Riccia marginata Lindb. was described by S. O. Lindberg (1877) from the outskirts of the town of Sortavala near the north shore of Lake Ladoga, Republic of Karelia, Russia. The species has been forgotten in most recent liverwort accounts of Europe, including Russia. Lectotypification of R. marginata is provided. R. marginata shares most characters with R. beyrichiana Hampe ex Lehm. It differs from “typical” plants of R. beyrichiana in having smaller spores, with ± distinctly finely areolate to roughly papillose proximal surfaces and a narrower and shorter thallus, as well as in scarcity or absence of marginal hairs. It may represent continental populations of the suboceanic-submediterranean R. beyrichiana, known in Russia from the Leningrad Region and Karelia only. The variability of spore surfaces in R. beyrichiana is discussed and illustrated by SEM images. A comparison with the spores of R. bifurca Hoffm. is provided. The question how distinct R. marginata is from R. beyrichiana needs to be clarified by molecular studies in the future, when adequate material is available. R. marginata is for the time being, provisionally, included in R. beyrichiana.

Conflict, Population Movement, and Microscale Social Networks in Northern Iroquoian Archaeology

2021 ◽  
Vol 86 (2) ◽  
pp. 350-367
Author(s):  
Jennifer Birch ◽  
John P. Hart
Keyword(s):  
Social Networks ◽  
Sixteenth Century ◽  
Lake Ontario ◽  
Population Movement ◽  
Network Ties ◽  
The West ◽  
Local Networks ◽  
North Shore ◽  
The North ◽  
Specific Sequences

We employ social network analysis of collar decoration on Iroquoian vessels to conduct a multiscalar analysis of signaling practices among ancestral Huron-Wendat communities on the north shore of Lake Ontario. Our analysis focuses on the microscale of the West Duffins Creek community relocation sequence as well as the mesoscale, incorporating several populations to the west. The data demonstrate that network ties were stronger among populations in adjacent drainages as opposed to within drainage-specific sequences, providing evidence for west-to-east population movement, especially as conflict between Wendat and Haudenosaunee populations escalated in the sixteenth century. These results suggest that although coalescence may have initially involved the incorporation of peoples from microscale (local) networks, populations originating among wider mesoscale (subregional) networks contributed to later coalescent communities. These findings challenge previous models of village relocation and settlement aggregation that oversimplified these processes.

Depositional environments of limestones from the Taiyuan Formation in the North China Block interpreted from REE proxies

2020 ◽  
Vol 35 (2) ◽  
Author(s):  
Dawei Lv ◽  
Wengui Fan ◽  
John I. Ejembi ◽  
Dun Wu ◽  
Dongdong Wang ◽  
...  
Keyword(s):  
North China ◽  
Depositional Environments ◽  
North China Block ◽  
The North ◽  
Taiyuan Formation

Depositional environments and paleogeography in the Albian Moosebar Formation and adjacent fluvial Gladstone and Beaver Mines formations, Alberta

1984 ◽  
Vol 21 (6) ◽  
pp. 698-714 ◽  
Author(s):  
David R. Taylor ◽  
Roger G. Walker
Keyword(s):  
Brackish Water ◽  
Late Jurassic ◽  
Major Change ◽  
Depositional Environments ◽  
Fluvial Deposits ◽  
Maximum Thickness ◽  
The North ◽  
Major Exception ◽  
Flow Directions ◽  
Sand Bodies

The marine Moosebar Formation (Albian) has a currently accepted southerly limit at Fall Creek (Ram River area). It consists of marine mudstones with some hummocky and swaley cross-stratified sandstones indicating a storm-dominated Moosebar (Clearwater) sea. We have traced a tongue of the Moosebar southward to the Elbow River area (150 km southeast of Fall Creek), where there is a brackish-water ostracod fauna. Paleoflow directions are essentially northwestward (vector mean 318°), roughly agreeing with turbidite sole marks (329°) in the Moosebar of northeastern British Columbia.The Moosebar sea transgressed southward over fluvial deposits of the Gladstone Formation. In the Gladstone, thick channel sands (4–8 m) are commonly multistorey (up to about 15 m), with well developed lateral accretion surfaces. The strike of the lateral accretion surfaces and the orientation of the walls of channels and scours indicate northwestward flow (various vector means in the range 307–339°). The Moosebar transgression was terminated by construction of the Beaver Mines floodplain, with thick, multistorey sand bodies up to about 35 m thick. Flow directions are variable, but various vector means roughly cluster in the north to northeast segment. This indicates a major change in dispersal direction from the Gladstone and Moosebar formations.A review of many Late Jurassic and Cretaceous units shows a dominant dispersal of sand parallel to regional strike. This flow is mostly north-northwestward (Passage beds, Cadomin, Gladstone, Moosebar, Gates, Chungo), with the southeasterly dispersal of the Cardium being the major exception. Only at times of maximum thickness of clastic input (Belly River and higher units, and possibly Kootenay but there are no published paleocurrent data) does the sediment disperse directly eastward or northeastward from the Cordillera toward the Plains.

Seismicity and faulting in the Charlevoix zone of the St. Lawrence Valley

1984 ◽  
Vol 74 (2) ◽  
pp. 595-603
Author(s):  
F. M. Anglin
Keyword(s):  
Active Zone ◽  
Continuous Monitoring ◽  
North Shore ◽  
The North ◽  
Earthquake Zone ◽  
St Lawrence River

Abstract Continuous monitoring of the seismically active Charlevoix zone since late 1977 has delineated the boundaries of the earthquake zone under the north shore and has enabled an association to be made with surface mapped faults that strike along the St. Lawrence Valley and dip to the southeast. Within the active zone, aseismic volumes are found under parts of the St. Lawrence River and another elongated zone of activity is found to the southeast on unmapped faults dipping under the river. The previous suggestions that the activity is related to old rift faults, which have been later weakened by a meteor impact, would seem to be upheld.

scholarly journals Mass mortality of Northern Map Turtles (Graptemys geographica)

2015 ◽  
Vol 129 (1) ◽  
pp. 80 ◽  
Author(s):  
Jordan Catrysse ◽  
Emily Slavik ◽  
Jonathan Choquette ◽  
Ashley E. Leifso ◽  
Christina M. Davy
Keyword(s):  
Lake Erie ◽  
Mass Mortality ◽  
Species At Risk ◽  
Long Term Effects ◽  
North Shore ◽  
The North ◽  
The Poor ◽  
Map Turtles ◽  
Graptemys Geographica

We report a mass mortality of Northern Map Turtles (Graptemys geographica [LeSueur, 1817]) on the north shore of Lake Erie, Ontario, Canada. Thirty-five dead adult females were recovered from a nesting area over a period of four weeks. Predation and boat strikes were both excluded as potential cause of death, but the actual cause could not be determined because of the poor condition of the carcasses. Other possible explanations for the mortality include poisoning, drowning, and infection with an unidentified pathogen. Mass mortality in long-lived species, such as turtles, can have long-term effects on population growth and is a cause for concern in a species at risk.

Acentropus niveus (Oliv.) (Lepidoptera: Pyralidae) on the north shore of Lake Erie with a consideration of its distribution in North America

1950 ◽  
Vol 82 (12) ◽  
pp. 250-252 ◽  
Author(s):  
W. W. Judd
Keyword(s):  
North America ◽  
Green Alga ◽  
Lake Erie ◽  
Filamentous Green Alga ◽  
North Shore ◽  
The North ◽  
Lepidoptera Pyralidae ◽  
Shallow Bay ◽  
The Village ◽  
The Waves

On July 12, 1950 a collection of adults of the moth Acentropus niveus (Oliv.) was made on the north shore of Lake Erie near the village of South Cayuga, Ontario (Maps A, B-3). At the southern limits of the townships of Dunn and South Cayuga (Haldimand County) a shallow bay extends for a distance of about two miles along the shore of the lake (Map A). Along this bay is a sandy or gravelly beach ten to twenty yards wide backed by a cliff of clay that rises abruptly above the beach. On the day the collections were made the sky was clear and a brisk southerly breeze was causing waves to wash on the beach. The action of the waves had deposited debris, consisting largely of tangled masses of a filamentous green alga and exuviae of the mayfly Hexagenia occulta, in a windrow six inches to two feet wide along the shore. The moths ere found in this debris, most of them lying dead and with bedraggled wings, while some lay on their backs with wings stuck to the damp surface and with legs kicking and a few were crawling about on the debris.

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