Lower Till Research Articles

BIOLOGICAL CONTROL OF CODLING MOTH, CYDIA POMONELLA (L.) IN APPLE ORCHARDS OF BULGARIA USING GINKO® DISPENSERS

The codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), is a significant pest of pome fruit and walnut orchards worldwide and it is a particular problem in Bulgaria. Codling moth resistance to many insecticides has been recently detected in Bulgaria. Codling moth (CM) mating disruption with Ginko® dispensers was evaluated in four successive years from 2019 to 2022 as part of an anti-resistance strategy. In an isolated 3 ha apple orchard in the Plovdiv district of South-Central Bulgaria, close to the town of Perushtitsa, field tests were conducted for the control of the codling moth (CM), C. pomonella, via mating disruption (MD) using pheromone Ginko® dispensers. The pheromone dispensers were hung in the upper third of tree canopies with a density of 500 dispensers/ha before CM flight started. Dynamics of CM flights was monitored by pheromone traps installed in the trial plot and in a conventionally treated reference orchard. Two types of baits were used in the traps: PHEROCON® CM L2–codlemone lures and PHEROCON® CM DA COMBO-P + AA lures (Trécé Inc., USA) in the orchards for mating disruption. The PHEROCON® CM L2 lures were changed at 4-week intervals and PHEROCON® CM DA COMBO-P + AA lures at 8-week intervals. PHEROCON® VI Delta sticky traps baited with PHEROCON CM DA COMBO- P + AA lures and standard CM L2 caps were installed, for comparison, in a reference orchard located in the Plovdiv region. Fruit infestation was periodically assessed till the harvest time. In both years fruit damage remained lower till late July and increased slightly only in August. At harvest, fruit damage remained below 1%. It was obvious that mating disruption could be useful strategy for the control of codling moth in Bulgarian apple orchards, specifically when the plot is isolated from external sources of infestation and the population density of the pest is low.

Quadratus Lumborum Block for Patients Undergoing Percutaneous Nephrolithotomy: A Randomized Controlled Study.

Background:Recent studies have supported the use of quadratus lumborum block (QLB) for postoperative analgesia for patients undergoing renal surgery.Aims:The aim was to study the efficacy of posterior QLB for postoperative analgesia in patients undergoing percutaneous nephrolithotomy (PCNL).Settings and Design:This trial was a hospital-based, randomized, double-blind, controlled, prospective study.Materials and Methods:Forty patients aged from 18 to 60 years, belonging to the American Society of Anesthesiologists physical status I–III and scheduled for unilateral PCNL under spinal anesthesia were administered ultrasound-guided posterior QLB with 30 ml of either 0.2% ropivacaine (Group Q) or normal saline (Group C) after the subarachnoid block. Duration of analgesia was the primary outcome variable.Statistical Analysis Used:Data were compiled in Microsoft Excel, and analyses were performed in SPSS (version 24.0.0.0; IBM, Armonk, New York, USA). Unpaired t-test, Mann–Whitney U test, and Fisher's exact test were used for the comparison of continuous, ordinal, and categorical data, respectively.Results:Duration of analgesia was significantly longer in Group Q (1167.10 ± 89.74 vs. 290.25 ± 47.38 min), as compared to Group C. Except at the end of the surgery, visual analog scale at rest and on movement was significantly lower till 20th h in Group Q. Patient satisfaction was better, and analgesic consumption was lower in Group Q. Side effects were similar in both groups.Conclusions:QLB provides good quality, and prolonged duration of postoperative analgesia compared to placebo for PCNL, but more large-scale studies are needed to recommend it for routine use.

Acute responses of spotted snakehead (Channa punctata) to salinity stress: A study of a freshwater fish to salinity challenges during intrusion of saline water

A climate driven changes in the coastal region of Bangladesh is saltwater intrusion in freshwater, which may directly affect the fishery production as well as economy and food security. Investigation on effect of different concentration of salinities (0, 5, 10, and 15ppt) on hemato-biochemical parameters, behavioral responses and gill morphology at certain time intervals (1, 6, 12, 24, 36, 48, and 72 h) were observed in a spotted snakehead, Channa punctata. In the present study the biochemical parameter and glucose exposed a significant (p <0.05) changes associated with different exposures at different time intervals. The hematological data of C. punctata revealed significant (p <0.05) decrease in red blood cell (RBC) count. The hemoglobin level in every treatment was lower till 24 h and then it increased up to 48 h but white blood cell (WBC) count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) showed significant (p <0.05) increase compared to the control. Increase and decrease of hematological indices expressed that fish exposure to different salinities were under stress. Unusual behavioral responses with various pathological signs in gills were also perceived. The results specified that the intrusion of saline water into the freshwater have deleterious effects on the hemato-biochemical parameters including gill morphology and behavior. So, the intrusion of saline water should be controlled to avert the losses.

New interglacial deposits from Copenhagen, Denmark: marine Isotope Stage 7

During a pre‐site survey and construction of a new metro route and station in Copenhagen, fossiliferous organic‐rich sediments were encountered. This paper reports on multidisciplinary investigations of these organic sediments, which occurred beneath a sediment succession with a lower till, glacifluvial sand and gravel, an upper till and glacifluvial sand. The organic sediments were underlain by glacifluvial sand and gravel. The organic‐rich sediments, which were up to 0.5 m thick, accumulated in a low‐energy environment, possibly an oxbow lake. They were rich in plant fossils, which included warmth‐demanding trees and other species, such as Najas minor, indicating slightly higher summer temperatures than at present. Freshwater shells were also frequent. Bithynia opercula allowed the sediments to be put into an aminostratigraphical framework. The amino acid racemization (AAR) ratios indicate that the organic sediments formed during Marine Isotope Stage 7 (MIS 7), which is consistent with optically stimulated luminescence dating that gave ages of 206 and 248 ka from the underlying minerogenic deposit. The assemblages from Trianglen are similar to interglacial deposits from the former Free Port (1.4 km away) in Copenhagen, except that Corbicula and Pisidium clessini were not found at Trianglen. The presence of these bivalves at the Free Port and the ostracod Scottia tumida at Trianglen indicates a pre‐Eemian age. AAR data from archived Bithynia opercula from the Free Port were almost identical to those from Trianglen, indicating that the two sites are contemporary. We suggest the Trianglen interglacial be used as a local name for the MIS 7 interglacial deposits in Copenhagen. MIS 7 deposits have rarely been documented from the region, but MIS 7 deposits may have been mistaken for other ages. The use of AAR ratios in Bithynia opercula has a great potential for correlation of interglacial non‐marine deposits in mainland northern Europe.

Features of disjunctive tectonics of Krivoy Rog iron ore area

The article describes the features of display of faults on the territory of Kryvyi Rih mining area, characteristic of which is different by complicated tectonic structure and covers the main stages of the formation of the crust from the lower Archaean till Late Proterozoic. Faults in the form of wide zones of concentration of gaps, fractures, mylonitization, cataclase, brecciation, magmatism, metamorphism, play a major role in formation of the modern fold-block structure of Kryvbas are well traced in geophysical fields. The main fault structure of the district is the trans-regional deep Krivoy Rog-Kremenchug fault that within Krivbass is presented by multiaxial system of faults: western axis — West fault; the central axis — Tarapakovsky fault; Eastern axis — Saksagansky and East faults. Almost all regional faults consist of two or three closely spaced parallel ruptures. By length, the inner overlay, behavior in geophysical fields in Krivbass the faults are subdivided into three groups: submeridional, corresponding to general spread of the main folded structures; diagonal, corresponding to the spread of the basic fold structures; sublatitudinal that are transverse to the spread of folded structures.

Imaging Drumlin Architecture with Electrical Resistivity

Geomorphologists may use the knowledge of interior structure of drumlins to infer finer-scale dynamics of glaciers. An electrical resistivity imaging study was carried out to investigate the interior architecture of a drumlin near UCCT seismic station located in the premises of the University Connecticut. Apparent resistivity measurements collected from an 81 m-long dipole-dipole electrode array oriented along the longer axis of the drumlin were inverted to obtain a subsurface model. The model consists of four layers of different resistivity values. These results are used to infer a glacial depositional sequence of younger upper till and older lower till separated by a transition layer. Evidence for a basement crystalline rock core was not found at the maximum penetration depth of 17 m.

Postnatal Pancreatic Islet β Cell Function and Insulin Sensitivity at Different Stages of Lifetime in Rats Born with Intrauterine Growth Retardation

Epidemiological studies have linked intrauterine growth retardation (IUGR) to the metabolic diseases, consisting of insulin resistance, type 2 diabetes, obesity and coronary artery disease, during adult life. To determine the internal relationship between IUGR and islet β cell function and insulin sensitivity, we established the IUGR model by maternal nutrition restriction during mid- to late-gestation. Glucose tolerance test and insulin tolerance test(ITT) in vivo and glucose stimulated insulin secretion(GSIS) test in vitro were performed at different stages in IUGR and normal groups. Body weight, pancreas weight and pancreas/body weight of IUGR rats were much lower than those in normal group before 3 weeks of age. While the growth of IUGR rats accelerated after 3 weeks, pancreas weight and pancreas/body weight remained lower till 15 weeks of age. In the newborns, the fasting glucose and insulin levels of IUGR rats were both lower than those of controls, whereas glucose levels at 120 and 180 min after glucose load were significantly higher in IUGR group. Between 3 and 15 weeks of age, both the fasting glucose and insulin levels were elevated and the glucose tolerance was impaired with time in IUGR rats. At age 15 weeks, the area under curve of insulin(AUCi) after glucose load in IUGR rats elevated markedly. Meanwhile, the stimulating index of islets in IUGR group during GSIS test at age 15 weeks was significantly lower than that of controls. ITT showed no significant difference in two groups before 7 weeks of age. However, in 15-week-old IUGR rats, there was a markedly blunted glycemic response to insulin load compared with normal group. These findings demonstrate that IUGR rats had both impaired pancreatic development and deteriorated glucose tolerance and insulin sensitivity, which would be the internal causes why they were prone to develop type 2 diabetes.

Reconstructing flow paths of the Middle Pleistocene British Ice Sheet in central-eastern England: the application of regional soil geochemical data

High-density regional geochemical data for surface soils in central England and East Anglia reveal that much of their geochemical character is inherited from the tills that they are developed upon. Multivariate statistical analysis highlighted three significant element associations of Al–Fe–Ga–K–La–Mg–Rb, Ca–Sr and K–Fe accounting for almost 93% of the geochemical variability of soils derived from tills. Provenancing the geochemical signatures of the latter elements enabled the construction of ice flow paths associated with two different Middle Pleistocene ‘chalky’ till sheets. A lower till sheet relating to ‘Pennine’ ice flowing from west to east across the region, and an upper till sheet deposited by North Sea ice moving into northern East Anglia, and to the west of the Fen Basin, before fanning-out across central England. Overall, geochemical signatures of different till units are largely derived from local bedrock sources, with dilution and a new geochemical signature acquired as the ice flows over and incorporates new bedrock lithologies. The results show that high resolution soil geochemical data provides a further proxy with which the flow paths of former ice sheets can be delineated.

Lithological and petrographic features of tills in the Koźmin region and their value for stratigraphical interpretation of glacial Lake Koźmin deposits, Central Poland

Joanna Petera-Zganiacz Czubla P., Forysiak J., Petera-Zganiacz J. Lithological and petrographic features of tills in the Koźmin region and their value for stratigraphical interpretation of glacial Lake Koźmin deposits, Central Poland. Geologija. Vilnius. 2010. Vol. 52. No. 1–4(69–72). P. 1–8. ISSN 1392-110X In the middle section, the Warta River valley runs through the Adamow graben. Th e graben was characterized by subsidence since the end of the Paleogene and favoured accumulation during the Neogene and the Quaternary. Th e Quaternary deposits consist of several till horizons separated mainly by a series of fl uvioglacial sand and a thick series of glaciolacustrine sediments. Th e research was concentrated on three upper levels of tills and selected series of sand available in Koźmin and Koźmin-Polnoc “Adamow” opencast mines. Th e lithological, petrographical features and long-axis azimuth of pebbles were analyzed. Th e results showed that the lower till could be dated to the Elsterian, middle till to the Wartanian, and the upper till is probably also Wartanian. Glaciolacustrine deposits which fi lled the erosional form and appeared in the middle till correlate with the end of the Wartanian.

Thoracic epidural analgesia in obese patients with body mass index of more than 30 kg/m 2 for off pump coronary artery bypass surgery

Perioperative Thoracic epidural analgesia (TEA) is an important part of a multimodal approach to improve analgesia and patient outcome after cardiac and thoracic surgery. This is particularly important for obese patients undergoing off pump coronary artery bypass surgery (OPCAB). We conducted a randomized clinical trial at tertiary care cardiac institute to compare the effect of TEA and conventional opioid based analgesia on perioperative lung functions and pain scores in obese patients undergoing OPCAB. Sixty obese patients with body mass index >30 kg/m2 for elective OPCAB were randomized into two groups (n=30 each). Patients in both the groups received general anesthesia but in group 1, TEA was also administered. We performed spirometry as preoperative assessment and at six hours, 24 hours, second, third, fourth and fifth day after extubation, along with arterial blood gases analysis. Visual analogue scale at rest and on coughing was recorded to assess the degree of analgesia. The other parameters observed were: time to endotracheal extubation, oxygen withdrawal time and intensive care unit length of stay. On statistical analysis there was a significant difference in Vital Capacity at six hours, 24 hours, second and third day postextubation. Forced vital capacity and forced expiratory volume in one second followed the same pattern for first four postoperative days and peak expiratory flow rate remained statistically high till second postoperative day. ABG values and PaO2/FiO2 ratio were statistically higher in the study group up to five days. Visual analogue scale at rest and on coughing was significantly lower till fourth and third postoperative day respectively. Tracheal extubation time, oxygen withdrawal time and ICU stay were significantly less in group 1. The use of TEA resulted in better analgesia, early tracheal extubation and shorter ICU stay and should be considered for obese patients undergoing OPCAB.

Проискождение друмлинов около збуйно (Центральная Польша)

Drumlins at Zbojno, Dobrzyn Lakeland, are located in a channel-like terminal basin, in the proximal part of the Chrostkowo end moraines. A fragment of the drumlin fi eld was examined in detail. Th e drumlins are elongated ridges, parallel to one another and to the basin margins. Th eir orientation is parallel to perpendicular with regard to the presumed regional direction of the ice sheet advance. Th e drumlins’ geological structure is tripartite, including a lower till, a glaciofl uvial core and a covering upper till. Georadar examination indicated the presence and extension of glaciotectonic deformations of the lower till. It is squeezed up to 3 m above its primary setting and forms protodrumlins that have not been, however, the bed bumps that stimulated a lee-side deposition. Protodrumlins are usually absent along a drumlin axis, but they occur also in pairs. Th ey could both initiate but also terminate drumlin development when thawing appeared in the subglacial zone and the ice body was disintegrated into dead-ice blocks. Glaciofl uvial cores are less deformed than the lower till: their sediments are stratifi ed, but commonly uplift ed towards a protodrumlin.

The Sangamonian Pointe-Fortune Site, Ontario-Québec Border

Inter-till sediments (Units 2, 3, 4) in a sand pit located 115 km east of Ottawa, Ontario, contain a predominance of deciduous tree pollen including oak. elm, beech and hickory {Quercus, Ulmus, Fagus, and Carya) and minor amounts of basswood, ash and sweetgum (TiHa, Fraxinus and Liquidambar). Unit 4 also contains macrofossils of several plant taxa which presently do not grow much north of the site. The fossils portray an inter-glacial environment (the Sangamonian) with conditions as warm as or warmer than the present in the area. By contrast, overlying Unit 4a reveals a dominance of boreal indicators such as pollen of spruce, pine, willow and alder (Picea, Pinus, Salix and Alnus) and the beetles, Bembidion transparens, Eucnecosum, and Olophrum boréale. Unit 4a fossils indicate a climate that was colder than at present but no colder than the climate of central Québec - suggesting a correlation with the waning phase of the warm interval, or alternatively, with the St. Pierre Interstade of the St. Lawrence Lowlands. Thus the lower till is interpreted as lllinoian in age; the upper till may be Middle to Late Wisconsinan or Early to Late Wisconsinan.

Glacial History and Stratigraphy of Northwestern New Brunswick

Au cours du Wisconsinien supérieur, deux mouvements glaciaires majeurs caractérisent le nord-ouest du Nouveau-Brunswick et les environs : une première phase pendant laquelle les mouvements glaciaires ont été déterminés par l'interaction d'écoulements à partir de centres d'accumulation locaux et par l'invasion glaciaire laurentidienne, puis une phase plus récente au cours de laquelle un nouveau mode d'écoulement glaciaire s'est élaboré en réponse à l'affaissement qui a suivi la hausse du niveau marin. Au cours de cette dernière phase la ligne de partage des glaces, qui s'est créée dans les Appalaches, s'étendait de l'Estrie (Québec), à travers le Maine et le Nouveau-Brunswick, jusqu'en Gaspésie. Le remblayage de la vallée sur une épaisseur de 60 m, qui s'est produit dans une grande partie du bassin de drainage du Saint-Jean, a précédé la dernière glaciation. Ce remblayage est constitué de dépôts de lac glaciaire et d'écoulement fluviatile et comprend également un pénultième till inférieur mis en place par un glacier qui se déplaçait d'abord vers l'E, puis, plus tard, probablement vers le SSE. Les terrasses le long du Saint-Jean, au sud de Grand Falls, sont essentiellement des formes d'érosion. Ces terrasses d'origine postglaciaire ont été formées en même temps que les chutes et la gorge à Grand Falls.

Till Stratigraphy and Late Wisconsinan Deglaciation of Southern Maine: A Review

At least two glaciations are recorded by the till stratigraphy of southern Maine. A more deeply weathered lower till is tentatively correlated with the early Wisconsinan (or older) Nash Stream Till in New Hampshire and its inferred equivalents in southern New England and Québec. The Laurentide Ice Sheet flowed south-southeastward across southern Maine in late Wisconsinan time and deposited the upper till. By about 14,000 years ago the ice sheet started to recede from the Maine coast, and the high peaks of the Mahoosuc Range emerged as nunataks in western Maine. Marine transgression accompanied déglaciation of lowland areas of southern Maine, with deposition of end moraines, deltas, and subaqueous outwash along the active ice margin, while thick clay deposits of the Presumpscot Formation accumulated on the ocean floor. The ice margin retreated quickly, reaching the marine limit in central Maine by 13,000 yr BP. The Pineo Ridge moraine system in eastern Maine, formerly thought to represent a major readvance, is reinterpreted as a glacial stillstand near the marine limit. Deglaciation inland from the marine limit in eastern and southwestern Maine occurred by recession of an active ice margin in some areas, and elsewhere by stagnation and downwasting of ice that was separated from the active ice sheet. Southern Maine was ice-free by 12,000 yr BP. but marine submergence persisted until about 11,000 years ago in the southwestern coastal lowland.

Upland Controls on the Hydrological Functioning of Riparian Zones in Glacial Till Valleys of the Midwest1

Abstract: Identifying relationships between landscape hydrogeological setting, riparian hydrological functioning and riparian zone sensitivity to climate and water quality changes is critical in order to best use riparian zones as best management practices in the future. In this study, we investigate water table dynamics, water flow path and the relative importance of precipitation, deep ground water (DG) and seep water as sources of water to a riparian zone in a deeply incised glacial till valley of the Midwest. Data indicate that water table fluctuations are strongly influenced by soil texture and to a lesser extent by upland sediment stratigraphy producing seeps near the slope bottom. The occurrence of till in the upland and at 1.7‐2 m in the riparian zone contributes to maintaining flow parallel to the ground surface at this site. Lateral ground‐water fluxes at this site with a steep topography in the upland (16%) and loam soil near the slope bottom are small (&lt;10 l/d/m stream length) and intermittent. A shift in flow path from a lateral direction to a down valley direction is observed in the summer despite the steep concave topography and the occurrence of seeps at the slope bottom. Principal component and discriminant analysis indicate that riparian water is most similar to seep water throughout the year and that DG originating from imbedded sand and gravel layers in the lower till unit is not a major source of water to riparian zones in this setting. Water quality data and the dependence of the riparian zone for recharge on seep water suggest that sites in this setting may be highly sensitive to changes in precipitation and water quality in the upland in the future. A conceptual framework describing the hydrological functioning of riparian zones on this setting is presented to generalize the finding of this study.

First evidence of “in situ” Eemian sediments on the high plateau of Evian (Northern Alps, France): implications for the chronology of the Last Glaciation

A 2 m profile of organic sediments, interbedded between two tills, was taken from the Evian high plateau at Hameau de Maravant, 860 m a.s.l. (Haute-Savoie, Western Alps, France). Pollen, plant macrofossils and insect remains were used to reconstruct the local palaeoenvironment, which consisted of a moss and Carex mire, surrounded by a dense Abies and Picea mixed forest. Pollen and macrofossil data indicate that this peat layer was deposited at the end of the Eemian interglacial. The lower till should therefore be assigned to the penultimate glaciation and the upper till to the maximum extent of the Rhône glacier during the Würm. A comparison of the results with previous studies carried out in the Geneva area and other alpine valleys has yielded a detailed reconstruction of the past fluctuations of the Rhône glacier: 1. a first Early/Lower Würmian advance, reaching the region around Lyon; 2. a subsequent retreat of ice; 3. a second moderate readvance, restricted to the surroundings of Geneva, followed by a final deglaciation. A continuous lacustrine sequence has been obtained from the nearby Roseire peat-bog (890 m a.s.l). Pollen and radiometric results show the establishment of a former palaeolake during the Upper Pleniglacial, probably before ca. 22 450±850 cal years BP, thus implying that the high plateau was ice-free from that time. These new data appear to suggest that the maximal extension of the Rhône glacier occurred prior to the Last Glacial Maximum (OIS 2) and, according to a well-documented geomorphological context, probably during the Lower Würmian Pleniglacial.

Cardiorespiratory effects of diazepam-ketamine, xylazine-ketamine and thiopentone anesthesia in male Wistar rats-A comparative analysis

Several anesthetics are known to cause respiratory and cardiovascular depression in humans and animals; but, these diverse effects have not been extensively investigated in laboratory rodents. The objective of this study is to choose a suitable anesthetic combination for use in surgical models eg. coronary artery ligation in rats. Male Wistar rats were anesthetized with three different drugs viz. diazepam-ketamine (DK) (2.5 mg/Kg, intraperitoneally (i.p); 50 mg/Kg, i.p), xylazine-ketamine (XK) (5 mg/Kg i.p; 50 mg/Kg i.p) and thiopentone (T) (40 mg/Kg i.p) and the respiratory and cardiovascular functions were assessed after coronary artery ligation. Heart rate (HR), mean arterial pressure (MAP), partial pressure of carbon dioxide (PaCO 2), partial pressure of oxygen (PaO 2), oxygen saturation percentage (O 2 sat (%)), arterial blood pH and rectal body temperature were studied in detail. During the anesthetic regime, HR was lower till 60 min in XK and T ligated group (333 ± 6; 304 ± 8 beats/min) and it was near normalcy in the case of DK ligated group (394 ± 6 beats/min). Significant respiratory depression was particularly reflected in the T ligated group with an increase in PaCO 2 at 30 min (40.32 ± 2.64 mmHg), which decreased to 38.2 ± 2.23 mmHg at 60 min. Throughout the investigation, DK showed the least overall effects compared to XK and T on respiratory functions. Thus, DK could be considered to be a suitable anesthetic for use in a surgical model such as coronary artery ligation in albino rats.

Fabric, paleomagnetism, and interpretation of pre-illinoian diamictons and paleosols on Cloudy Ridge and Milk River Ridge, Alberta and Montana

Pebble fabrics and sedimentological properties indicate that pre-Wisconsinan diamictons (Kennedy Drift) on Cloudy Ridge (Alberta) and Milk River Ridge (Montana) are of glacial rather than colluvial origin. S1 and S3 eigenvalues of the upper units on the two ridges are typical of undeformed lodgement till whereas those of the lower unit on Milk River Ridge are typical of glacigenic sediment flow. Other properties, including compact matrices, striations on stones, mean pebble dip angles, and Schmidt equal-area stereonet patterns, suggest each unit is lodgement or basal till. Pedogenic features indicate weathering zones capping the tills are paleosols. Degree of rubification, clay, iron and aluminum buildup, and clay mineral alteration resembles those of very strongly developed soils formed in warmer and moister environments. The argument that “soil-like features” of the Cloudy Ridge unit resulted from post-burial diagenesis is disproven because nearly identical paleosols occur at the surface on Milk River Ridge and other interfluves to the south. Each unit examined has normal polarity. Based on comparisons with similar till/paleosol sequences exposed in Kennedy Drift sections on nearby interfluves, the Cloudy Ridge till and the upper till on Milk River Ridge were probably deposited during the early to middle Bruhnes Normal Chron (780 ka to present) whereas the lower till on Milk River Ridge is of earlier Brunhes age or dates back to the Olduvai (1.98 to 1.76 Ma) Normal Subchron or the Gauss Normal Chron (3.6 to 2.6 Ma).

Characterizing the hydrogeology of a complex clay-rich aquitard system using detailed vertical profiles of the stable isotopes of water

High-resolution 1D profiles of the stable isotopes of porewater (δ2H and δ18O) obtained by direct porewater-equilibration of core samples were used to identify hydrogeologic zones in a thick, complex, till aquitard system in Saskatchewan, Canada. Detailed 1D isotope profiles revealed the presence of three distinct hydrogeological zones: an upper (5–10 m), an intermediate (10–30 m), and a lower (30–62.5 m) till zone. The upper hydrogeological zone was controlled by a sand layer having a high hydraulic conductivity (K). The lack of vertical variability in the stable isotope data in the intermediate zone suggested groundwater flow and solute transport was controlled by a system of interconnected vertical fractures and lateral sand layers. The curved shape of the isotope profile in the lower till zone suggested that solute transport in this zone was controlled mainly by molecular diffusion. We show that high-resolution vertical stable isotope profiles of porewater obtained from core samples and direct equilibration yield cost-effective and invaluable hydrogeologic information on groundwater flow in aquitard systems that cannot be realistically obtained by construction of costly conventional piezometer bundles (i.e. δ2H and δ18O analyses of water samples and K determinations). Further, the direct equilibration approach overcomes the problem of piezometer leakage in low K aquitards.

Characterizing the hydrogeology of a complex clay-rich aquitard system using detailed vertical profiles of the stable isotopes of water

High-resolution 1D profiles of the stable isotopes of porewater (δ 2H and δ 18O) obtained by direct porewater-equilibration of core samples were used to identify hydrogeologic zones in a thick, complex, till aquitard system in Saskatchewan, Canada. Detailed 1D isotope profiles revealed the presence of three distinct hydrogeological zones: an upper (5–10 m), an intermediate (10–30 m), and a lower (30–62.5 m) till zone. The upper hydrogeological zone was controlled by a sand layer having a high hydraulic conductivity ( K). The lack of vertical variability in the stable isotope data in the intermediate zone suggested groundwater flow and solute transport was controlled by a system of interconnected vertical fractures and lateral sand layers. The curved shape of the isotope profile in the lower till zone suggested that solute transport in this zone was controlled mainly by molecular diffusion. We show that high-resolution vertical stable isotope profiles of porewater obtained from core samples and direct equilibration yield cost-effective and invaluable hydrogeologic information on groundwater flow in aquitard systems that cannot be realistically obtained by construction of costly conventional piezometer bundles (i.e. δ 2H and δ 18O analyses of water samples and K determinations). Further, the direct equilibration approach overcomes the problem of piezometer leakage in low K aquitards.