Quaternary events in the Elkwater Lake area of southeastern Alberta

1986 ◽  
Vol 23 (12) ◽  
pp. 2024-2038 ◽  
Author(s):  
Willem J. Vreeken
Keyword(s):  
Volcanic Eruption ◽  
Middle Miocene ◽  
Lake Area ◽  
Present Level ◽  
Maximum Extent ◽  
The North ◽  
Green Lake ◽  
South Saskatchewan River ◽  
Late Wisconsinan ◽  
North And South

New data necessitate revisions in the Quaternary chronology of the Elkwater Lake area. Relicts of post-Middle Miocene preglacial erosion surfaces descend to the north and south from the Middle Miocene depositional surface on the Cypress Hills plateau. Both sets of surfaces are marked by oxidized weathering zones, locally culminating in relicts of preglacial paleosols. Both surfaces are overlain by a loess replete with cryogenic imprints. Deposition of this loess with cryogenic imprints shortly predates arrival of the Green Lake glacier at its terminus.The Green Lake end moraine marks the maximum extent of Laurentide ice in this area. Features previously attributed to the older Elkwater glacier can be explained with reference to proglacial meltwater action associated with the Green Lake glacier. The concept of Elkwater drift is no longer valid.Younger loesses, called upper loess, mantle nonglaciated terrain and the Green Lake end moraine and began accumulating just before Glacier Peak tephra was deposited (ca. 12 000 years ago). Because there is no evidence of weathering on the Green Lake end moraine beneath the upper loess, Green Lake drift dates from the late Wisconsinan. Most of the upper loess was deposited during the early Holocene and some since the Mazama volcanic eruption, 6600 years ago.Elkwater Lake reached its highest postglacial level, i.e., at least 6.6 m above the present level, well after the Mazama eruption, before spilling across the Green Lake end moraine into the Ross Creek system. This event irrevocably changed the regimen of Ross Creek, probably to its confluence with the South Saskatchewan River, at Medicine Hat.

scholarly journals The Archaeological Evidence of St. Clement of Ohrid’s Activities in the Ohrid Region

Slovene ◽  
2016 ◽  
Vol 5 (2) ◽  
pp. 136-178
Author(s):  
Pasko Kuzman
Keyword(s):  
Lake Area ◽  
Archaeological Evidence ◽  
The North ◽  
The Village ◽  
North And South ◽  
The Church ◽  
Archaeological Excavations

Among the activities of St. Clement of Ohrid was the construction of the church and monastery in Ohrid, which was carried out at the end of the 9th century at the location where some Byzantine basilicas had stood previously. As findings of archaeological excavations have shown, St. Clement first built a small triconch church at the location of the ruined basilica. This triconchos was later expanded by the addition of a capacious “pronaos” in inscribed-cross form, where St. Clement was interred. This “pronaos” was characterized by entrances on the north and south sides that were identical to those of the inscribed-cross church that existed near the village of Velcë along the Šušica River (in southern Albania) at the turn of the 9th‒10th century. During the tenure of Archbishop Dmitrios Chomatianos (1216–1236), the “pronaos” was replaced with a new church into which the relics of St. Clement were placed. In the Ottoman period, the Church and Monastery of St. Clement were disassembled to build a mosque. At the very beginning of the 10th century, the triconchal church in the Monastery of St. Clement served as a model for the church in the Monastery of St. Naum, in the southern part of the Ohrid lake area. The groundwork(s) of a further church in a triconchal shape, whose construction can be traced back to the time of St. Clement, has also been discovered at Gorica, near Ohrid. Ruins of yet another triconchal church which also belongs to the period under review can be found near the village of Zlesti, in the Dolna Debarca region, not far from Ohrid. In the vicinity of the village of Izdeglavje, in the Gorna Debarca region, there is also a church whose establishment is related to the activity of St. Clement of Ohrid as well.

scholarly journals The Hell Creek Formation, Montana: A Stratigraphic Review and Revision Based on a Sequence Stratigraphic Approach

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 435
Author(s):  
Denver Fowler
Keyword(s):  
South Dakota ◽  
Lake Area ◽  
Sequence Stratigraphic ◽  
Hell Creek Formation ◽  
Accommodation Space ◽  
The North ◽  
Marine Influence ◽  
Sequence Boundaries ◽  
North And South ◽  
Upper Maastrichtian

The Upper Maastrichtian fluvial Hell Creek Formation of the Fort Peck Lake area, Montana (and regional equivalents) is notable for its vertebrate fossils and for the K-Pg mass extinction at or near its upper contact. Despite intense study, internal stratigraphy of the Hell Creek Formation is still poorly constrained, hindering study. This work reviews the stratigraphy of the Hell Creek Formation, as currently understood, and proposes important revisions to the recently proposed type section, particularly concerning complexity of the Hell Creek Formation basal contact. This work also subdivides the Montanan Hell Creek Formation into four 4th order depositional sequences, superimposed over a 3rd order marine transgression. Sequence boundaries are defined by four, laterally continuous disconformities formed by pauses in the creation of accommodation space, marked by overlying amalgamated channel complexes, or less commonly, correlative interfluve paleosols. Cyclicity in Montana may be correlative with similar 4th order cyclicity and marine influence documented in North and South Dakota, Alberta, and Saskatchewan. Magnetostratigraphy and new biostratigraphic data support correlation of the upper Montanan sequence with the North Dakotan Cantapeta tongue (and overlying fines) and Canadian Scollard and Frenchman Formations.

A reconstruction of glacial events in southeastern New Brunswick

1991 ◽  
Vol 28 (10) ◽  
pp. 1594-1612 ◽  
Author(s):  
Marc Foisy ◽  
Gilbert Prichonnet
Keyword(s):  
New Brunswick ◽  
Ice Flow ◽  
Ice Cap ◽  
The North ◽  
Lithostratigraphic Units ◽  
Glaciofluvial Deposits ◽  
Southern Border ◽  
Late Wisconsinan ◽  
Radial Outflow ◽  
North And South

Sedimentological and petrographical data obtained from five sections located north and south of the Caledonian Highlands in southeastern New Brunswick demonstrate the existence of three main till units and one glaciofluvial unit, which have been grouped in four distinct lithostratigraphic units. The lower till was deposited by a glacier that overrode the Caledonian Highlands from northwest to southeast and advanced as far as Nova Scotia during Middle(?) to Late Wisconsinan times. The overlying middle till from the north provides evidence that ice continued to advance across the Highlands from northwest toward southeast and then was partially overwhelmed by another glacier that was advancing southwest along the southern border of the Highlands: this glacier deposited a coeval middle till. During Late Wisconsinan deglaciation, ice separated into two masses: a residual ice cap with radial outflow from the Highlands; and a lobe in the Chignecto Bay, retreating toward the northeast. The existence of a plateau ice cap is demonstrated by the presence of till and glaciofluvial deposits in the upper part of all surveyed sections, and is supported by the sequence of ice flow patterns recorded by striae and the centrifugal distribution of meltwater flow indicators. The weak development of soils, the fresh appearance of till and morainic landforms, and the lack of periglacial features throughout the area, especially on the Highlands, all favour the interpretation that the Caledonian Highlands were not a nunatak during the glacial maximum of the Late Wisconsinan Substage.

scholarly journals Evidence for a hardwater radiocarbon dating effect, Wonder Lake, Denali national park and preserve, Alaska, U.S.A.

2002 ◽  
Vol 53 (3) ◽  
pp. 407-411 ◽  
Author(s):  
Jonathan K. Child ◽  
Al Werner
Keyword(s):  
National Park ◽  
Sediment Cores ◽  
Pollen Record ◽  
Lake Area ◽  
Alaska Range ◽  
Radiocarbon Age ◽  
The North ◽  
Late Wisconsinan ◽  
Denali National Park ◽  
Age Estimates

Abstract Anderson et al. (1994) present a late Pleistocene/Holocene pollen record for lacustrine sediment cores retrieved from the north end of Wonder Lake, Denali National Park and Preserve, Alaska. Bulk radiocarbon age estimates obtained during their study suggest that either a Picea refugium persisted in the foothills of the north Alaska Range near Wonder Lake during the Late Wisconsinan, or that bulk radiocarbon age estimates are inaccurate. Subsequent cores recovered from Wonder Lake (and a near-by kettle pond) have been correlated to the Anderson et al. core and age dated using Atomic Mass Spectrometry (AMS) radiocarbon age estimates. AMS radiocarbon ages suggest that bulk radiocarbon ages from Anderson et al. (1994) are affected by hardwater conditions in Wonder Lake causing them to appear greater than 2000 14 C years too old. The corrected core chronology is consistent with documented regional vegetation changes during the glacial/interglacial transition and does not require a local Picea refugium in the Wonder Lake area during the Late Wisconsinan.

scholarly journals Development of Improved Characteristic Equations for Lake Rukwa in Tanzania

2019 ◽  
Vol 38 (1) ◽  
pp. 83-96
Author(s):  
Patric C. Valimba
Keyword(s):  
Change Point Analysis ◽  
Lake Area ◽  
Characteristic Equations ◽  
Surface Areas ◽  
Boundary Change ◽  
The North ◽  
Point Analysis ◽  
Contour Boundary ◽  
North And South ◽  
Topographical Maps

Often Lake Rukwa characteristics have been misreported in literature giving different volumes and surface areas at similar water surface elevations. This study aimed at establishing reliable lake characteristics elevation-area-storage equations for Lake Rukwa by utilising all available data and information to define the bathymetry and derive characteristic equations. A procedure was developed that combines historical lake extents, spot heights from topographical maps and surveyed lake bathymetry to define refined bathymetry to levels it has never reached. It combined spot heights around the lake and selected 13,934 surveyed points (from 107,938 available) within the lake confined by the 820 m land contour boundary and define topographical raster image, which was used to extract lake volumes and surface areas between the lowest point (778 m) and 820 m boundary. Change-point analysis was used to detect segmentation of the elevation-area and elevation-volume relationships, which were fitted to a shifted power model. Contours generated from a refined bathymetry raster indicated Lake Rukwa to comprise two north and south lake basins, which are separated by a ridge lying at an altitude of 794.3 m. The north and south lakes consist respectively of five (5) and three (3) deeper depressions (pools) paralleling the northwest- southeast Konongo Scarp, which are disconnected below altitudes 792 m (north) and 789.4 m (south). Characteristic elevation-area and elevation-volume equations are segmented for lake below ridge altitude (794.3 m) whereas single relationships prevail for a single Lake Rukwa. Comparison of lake volumes estimated by refined and old equations indicated underestimation of lake stored volumes between 782.2 m and 805.65 m altitudes and overestimation thereafter by the old equations although the under/over-estimation remained within 10% between 801 m and 812 m. Old elevation-area equations underestimate lake surface area of up to 796.8 m, thereafter overestimate the lake area up to an altitude of 804.85 m and above this altitude underestimation re-appear. The old equations under/over-estimation, however, remains within 11% for altitudes between 794.3 m and 810 m. The refined equations indicate surface areas of north and south lakes at ridge altitude to be 2,554.4 and 837.1 km2 , respectively forming a 3,391.5 km2 lake while at its highest recorded historical elevation of 804.69 m, Lake Rukwa is 183 km long and 17-51 km wide occupying an area of 5,614.7 km2 (north: 4,409.8 km2; south: 1,204.9 km2) and containing 58.243 km3 of water (north: 44.318 km3; south: 13.925 km3). The developed characteristic equations can be used for water management studies of Lake Rukwa.

The last glaciation of Marvin Peninsula, northern Ellesmere Island, High Arctic, Canada

1989 ◽  
Vol 26 (12) ◽  
pp. 2578-2590 ◽  
Author(s):  
Donald S. Lemmen
Keyword(s):  
High Arctic ◽  
Ellesmere Island ◽  
North Coast ◽  
Radiocarbon Dates ◽  
The North ◽  
Last Glaciation ◽  
Ice Retreat ◽  
Late Wisconsinan ◽  
Glaciomarine Sediments ◽  
North And South

The limit of the last glaciation on Marvin Peninsula, northernmost Ellesmere Island, is recorded by extensive ice-marginal landforms and early Holocene glaciomarine sediments. While glaciers occupied most valleys on the peninsula, other areas remained ice free, as did most of the adjacent fiords. Beyond the ice limit, sparse erratics and degraded meltwater channels within weathered bedrock are evidence of older, more extensive glaciation(s). Shorelines and marine shells 50 m above the limit of the Holocene sea along the north coast relate to these older glacial events.Thirty-four new radiocarbon dates provide a chronology of ice buildup and retreat. Glaciers reached their limit after 23 ka, and locally as late as 11 ka. This was achieved by both expansion of existing glaciers and accumulation on plateau and lowland sites, which are presently ice free. Late Wisconsinan climate was characterized by cold and extreme aridity. Five dates ranging from 11 to 31 ka BP on subfossil bryophytes suggest that ice-free areas were biologically productive throughout the last glaciation. Ice retreat and postglacial emergence had begun by 9.5 ka and was associated with a marked climatic amelioration. The deglacial chronology confirms a pronounced disparity in the timing of ice retreat on the north and south sides of the Grant Land Mountains.

Discovery of a Sphaeroschwagerina fusuline fauna from the Raggyorcaka Lake area, northern Tibet: implications for the origin of the Qiangtang Metamorphic Belt

2015 ◽  
Vol 153 (3) ◽  
pp. 537-543 ◽  
Author(s):  
YI-CHUN ZHANG ◽  
SHU-ZHONG SHEN ◽  
QING-GUO ZHAI ◽  
YU-JIE ZHANG ◽  
DONG-XUN YUAN
Keyword(s):  
Lake Area ◽  
Early Permian ◽  
Metamorphic Belt ◽  
Northern Tibet ◽  
The North ◽  
North And South

AbstractThe Qiangtang Metamorphic Belt (QMB) was considered to have either formed in situ by amalgmation of the North and South Qiangtang blocks or been underthrust from the Jinsha suture and exhumed in the interior of a single ‘Qiangtang Block’. A new Sphaeroschwagerina fusuline fauna discovered in the Raggyorcaka Lake area supports the interpretation that the North and South Qiangtang blocks were separated by a wide ocean during Asselian (Early Permian) time, indicating that the QMB was formed by the suturing of the Palaeotethys Ocean along the Longmu Co-Shuanghu suture.

Author response for "Geological and geophysical differences between the north and south sections of the Yap trench‐arc system and their relationship with Caroline Ridge subduction"

2020 ◽  
Author(s):  
Cheng‐Long Xia ◽  
Yan‐Peng Zheng ◽  
Bao‐Hua Liu ◽  
Qing‐Feng Hua ◽  
Kai Liu ◽  
...  
Keyword(s):  
Author Response ◽  
Ridge Subduction ◽  
The North ◽  
North And South
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