Tertiary Beds Research Articles

Formation Mechanisms of Some Features in Siliceous Upper Cretaceous-Lower Tertiary Beds of Jordan-Undulations, Geodes, Boudinages

Formation Mechanisms of Some Features in Siliceous Upper Cretaceous-Lower Tertiary Beds of Jordan-Undulations, Geodes, Boudinages

Abstract TP45: Promoting High Value Care For Stroke Patients Within A Stroke System Of Care: Reducing Unnecessary Hospital Transfers For Patients Not Taken For Thrombectomy

Introduction: High value care aims to provide the best patient outcomes while avoiding defects and waste. Our previous work determined that 39% of patients transferred for possible thrombectomy based on clinical criteria and CT only did not have a large vessel occlusion (LVO) which led to a health system-wide guideline to improve transfer selection by adding criteria for emergent CT angiography. This study aims to describe the impact of that guideline and reanalyze the reasons why patients transferred for consideration of thrombectomy do not receive the procedure. Methods: All patients transferred from within and outside of the health system as a potential thrombectomy candidate between 1/1/19- 6/30/21 were reviewed for reasons why thrombectomy was not pursued. Results: Over 30 months, 316 patients transferred for possible thrombectomy were not taken to the angio suite primarily due to absence of LVO on vessel imaging (26.3%), lack of suspicion of LVO on assessment (18%) and significant improvement in clinical symptoms (12%). Other reasons included too large of core infarct (13.3%), CT head ASPECT score (8.2%), lack of perfusion imaging mismatch (6.3%), poor baseline functional status (4.7%), lesion too distal (3.8%), ICH (3.2%), time since last known well (1.9%), chronic ICA occlusion preventing access to acute lesion (1.9%), and medically unstable (0.3%). Conclusions: Despite the institution of a system-wide protocol for acute CTA imaging to guide patient selection, the major reason for not proceeding to thrombectomy was still absence of LVO, some of which was related to out-of-system hospital transfers. Drawbacks of unnecessary patient transfer include increased cost of care, moving patients farther away from their home and family, and non-essential use of tertiary hospital bed space, particularly in the setting of a pandemic. Given the prevalence of potentially preventable unnecessary transfers, protocols that support in-the-field triage and transport based on clinical criteria alone, without CT or CTA, are destined to worsen health system efficiency and decrease the value of care for patients with major acuteischemic stroke.

1188. The Effect Of The COVID-19 Pandemic On Influenza-Related Hospitalization, Intensive Care Admission And Mortality In Canadian Children

BackgroundThe COVID-19 pandemic resulted in unprecedented implementation of wide-ranging public health measures globally. During the pandemic, dramatic decreases in seasonal influenza virus detection have been reported worldwide. Information on pediatric influenza-related hospitalizations is limited. We describe influenza-related hospitalization in Canadian children during the 2020/2021 influenza season compared to ten previous seasons.MethodsData on influenza-related hospitalizations, intensive care unit (ICU) admissions and in-hospital deaths in children across Canada were obtained from the Canadian Immunization Monitoring Program, ACTive (IMPACT). This national surveillance initiative comprises 90% of all tertiary care pediatric beds in Canada. The total study period included eleven influenza seasons from September 2010 to April 2021 inclusive. Time series modelling was used to compare trends in influenza-related hospitalizations during the 2020/2021 season (September 2020 to April 2021 inclusive) with the ten previous seasons.ResultsDuring the 2020/2021 influenza season there were no pediatric influenza infection-related hospitalizations. This was a significant decrease compared to the predicted total influenza-related hospitalizations for this period (p< 0.001). No pediatric ICU admission or deaths were reported for the 2020/2021 influenza season.ConclusionWe show complete absence of influenza infection-related hospitalization in children in Canada during the 2020/2021 season. This significant decrease is likely related in large part to non-pharmacological public health interventions implemented during the COVID-19 pandemic, although the potential role of viral interference is unknown. Our findings suggest measures such as use of facemasks, hand-washing, distancing and school closures may be beneficial for influenza control and mitigation of future influenza epidemics.Disclosures Helen E. Groves, PhD, MBBCh BAO, Abbvie (Other Financial or Material Support, Dr. Groves reports personal fees from Honoraria received from Abbvie for education meeting presentation, not relevant to the submitted work.) Jesse Papenburg, MD, AbbVie (Grant/Research Support, Other Financial or Material Support, Personal fees)Medimmune (Grant/Research Support)Sanofi Pasteur (Grant/Research Support)Seegene (Grant/Research Support, Other Financial or Material Support, Personal fees) Manish Sadarangani, BM BCh, DPhil, GlaxoSmithKline (Grant/Research Support)Merck (Grant/Research Support)Pfizer (Grant/Research Support)Sanofi Pasteur (Grant/Research Support)Seqirus (Grant/Research Support)Symvivo (Grant/Research Support)VBI Vaccines (Research Grant or Support) Shaun Morris, MD, MPH, DTM&H, FRCPC, FAAP, GSK (Speaker’s Bureau)Pfizer (Advisor or Review Panel member)Pfizer (Grant/Research Support)

Clinical decision support in a hospital electronic prescribing system informed by local data: experience at a tertiary New Zealand centre.

An electronic prescribing and administration (ePA) system has been progressively rolled out to Canterbury District Health Board (CDHB, Christchurch, New Zealand) public hospitals since 2014, and is currently used for around 1300 tertiary beds. ePA data can be used to monitor user behaviour, and to evaluate and inform the local customisation of clinical decision support (CDS) tools within the ePA system. To describe retrospectively illustrative vignettes of CDHB ePA analyses that have been used for CDS. Alerts were developed according to a set of common principles agreed upon by the CDHB CDS Working Group. Alerts were informed and evaluated by extracting and parsing data for various time periods during 2016 to 2018 from the CDHB ePA database. There was a median of 74 000 prescriptions a month. After examining 525 spironolactone prescriptions, the high dose alert threshold was set at 100 mg with an expected alert burden of 3%. The presence of a ceftriaxone shortage prescribing alert for 1 week was associated with a prescribing rate that was lower than 95% of the preceding 52 weeks. Following review of 367 fentanyl patch alerts, revision of the alert led to false positives falling from 43% to 3% (P < 0.0001). At the point of firing, 6% of antithrombotic drug interactions alerts led to immediate changes in prescriptions (94% overridden), and a further 22% were changed within 30 min after the alert. Local data extracts from ePA systems can inform iterative configuration of the software and monitor user behaviour.

5 Close to Home: Implementation of a transfer process for paediatric inpatients from tertiary to community care

Abstract Background Patients presenting to the emergency department who require inpatient care are either admitted to our tertiary care inpatient units or transferred directly to a community hospital. When patients appropriate for community care cannot be transferred due to a lack of community beds and instead remain in a tertiary care bed, there are palpable downstream effects on patient flow. A pre-study audit confirmed that, once admitted, transfers from the inpatient unit to a community bed are rare. This project aimed to improve access to tertiary care beds by increasing inpatient transfers to community hospitals. Objectives The project aimed to transfer 25% of all eligible patients from the Paediatric Medicine inpatient units to community hospitals over a 4-month period by identifying eligible patients and streamlining the transfer process. Design/Methods An Ishikawa diagram with input from inpatient physicians and nurses and community hospital colleagues identified 4 modifiable barriers. A process map was created along with a simplified transfer process. Medical teams and nurse leaders were provided with the charts of contact numbers, geographic locations and levels of care for community hospitals. Intake nurses tracked eligible patients. Encrypted text messages were sent to inpatient physicians on their mobile devices every morning reminding them to assess specific patients for transfer. The outcomes of all identified patients including process and balancing measures were tracked. Results Multiple PDSA cycles focused on improving the success of identifying eligible patients at multiple points in the process. The study’s outcome measure was the rate of successful inpatient transfers for all eligible patients. From November 2018 to March 2019, 120 patients were identified as eligible for transfer at the time of admission: 45 (37.5%) were discharged within 24 hours, 42 (35%) were not considered clinically appropriate for transfer by the attending physician and 33 were considered appropriate for transfer. Twenty-four were approached for transfer (72.7%); 9 were not approached for non-clinical reasons. Six (18.2%) refused transfer and 10 (30%) were successfully transferred. These rates were sustained over the study period. Conclusion A streamlined transfer process can improve patient flow, optimize utilization of tertiary care beds and provide care closer to home. A more robust method of tracking patients that could flag patients and send physicians electronic reminders is needed. Most importantly, optimal use of tertiary care beds requires a culture shift to ensure every patient is considered for transfer to the community when medically appropriate.

Going back to collections: a study case of the Florentino Ameghino collection housed in the Museo de La Plata (Argentina)

The historical Florentino Ameghino collection housed in the Museo de La Plata (Argentina) joined the 19th century international discussion about human antiquity. The collection comprises bones with evidences of anthropic modification from alleged Tertiary beds associated with extinct animals. According to the Argentinean naturalist Florentino Ameghino, these evidences proved the early presence of humans in the South America’s Southern cone. This analysis rules out the proposed intentionality behind the anthropic traces. Instead, most of the materials were remains of broken bones for marrow extraction. The revision of these historical collections is therefore crucial for obtaining up-to-date information to advance in current researches as methodologies to study them had highly developed in the last century. In this sense, museum collections become an alternative and powerful firsthand tool that preserves our non-renewable record of the past.

Sub-Surface Investigation Using Vertical Electrical Sounding: Chennai Metropolitan Area

The data or information on the sub-stratum, nature of aquifers, their spatial disposition, their hydrogeological characteristics and other information, are limited particularly in urban context. The study was performed in the Chennai metropolitan area. The objective of the study was to get the sub-surface information of the study area. The vertical electrical sounding was performed at ninety locations to identify the sub surface lithology. The Archaeans consisting of Charnockites, gneisses and dolerite occupy the southern part of the Metropolitan area. The lower portion of gondwanas belonging to the Talchir beds consist of light brown and green colored Shales occurring below the alluvium in the area between Nandanam on the east to Nandambakkam on the west. These Shales are overlying the older crystalline rocks. The lower portion of gondwanas belonging to the Talchir beds consist of light brown and green coloured Shales occurring below the alluvium in the area between Nandanam on the east to Nandambakkam on the west The Tertiary bed comprising friable white and reddish brown Sandstone occurs on the western side near Chembarambakkam and on the northwestern side between Thirunindravur and Villiwakkam. The thickness of the alluvium ranges between 5m on the southern side to a little more than 20m on the east central part of the Metropolitan area.

Variable Outcome in Quintuplets Pregnancy Based on Obstetric Care

The incidence of multiple pregnancies has increased dramatically over the last few years in developed countries, largely attributed to delayed childbearing and the increasing use of assisted reproduction technologies and ovulation inducing hormones. Relatively few countries have population-based statistics covering birth statistics. Of those that do, the numbers of quintuplet pregnancies rose sharply in the nineties while, at the same time, their delivery rates decreased greatly because of the use of fetal reduction. Fetal reduction is not possible or legal in some countries, Poland being one of them, and therefore obstetricians are faced with the challenges of quintuplet deliveries. Conservative treatment and management is difficult, and outcomes often vary greatly. Despite this, expert care provided at tertiary care centers can positively influence outcomes. The objective of this article is to present different care options and their consequences in two illustrative cases, as well as to establish a set of obstetric care and management goals that would allow prolongation of the gestation time. Quintuplet pregnancy is rare but poses relevant clinical problems to both the obstetrician and the neonatologist. It should be managed with close cooperation between all concerned. Due to the extreme and invariable risk of premature delivery associated with quintuplet pregnancies, we recommend early diagnosis, adequate prenatal care at one tertiary medical center, routine hospitalization and bed rest, repeated ante partum ultrasound surveillance with tests of fetal well-being, tocolytic therapy at first signs of the risk of premature labor, and specialized neonatology care after delivery.

Occurrence of zeolite in the Tertiary beds of the southern part of Gunma Prefecture

Occurrence of zeolite in the Tertiary beds of the southern part of Gunma Prefecture

Morphological and systematic reassessment of †Knightia brasiliensis Woodward, 1939 (Teleostei: Clupeiformes) from the Pliocene of Parnaíba Basin, northeastern Brazil

†Knightia brasiliensis, a small clupeoid fish found in the Tertiary beds of Nova Iorque, State of Maranhão (Brazil), is morphologically redescribed in detail. It is separated from nominal species of †Knightia, including the type-species †Knightia eoceana from the Lower Eocene of Wyoming, mainly by the absence of dorsal scutes, presence of two supramaxillae, and one epural, and is therefore placed in a new genus, †Paleopiquitinga gen. nov. The caudal skeleton of †Paleopiquitinga gen. nov. shows some advanced features (one epural, parhypurapophysis, and pleurostyle) in comparison with other well-known fossil clupeomorphs from the Cretaceous and Tertiary of South America and Africa, and a combination of features indicates the placement of †Paleopiquitinga gen. nov. within the family Clupeidae. Although uncertainties about polarity of characters within the Clupeidae render the relationships of †Paleopiquitinga gen. nov. difficult to establish at present, certain features indicate a close relationship with the extant Atlantic and East-Pacific genus Lile.

A new species of Argillochelys (Testudines: Cryptodira: Cheloniidae) from the Ouled Abdoun phosphate basin, Morocco

AbstractA new species of Argillochelys (Testudines: Cryptodira: Cheloniidae), A. africana n. sp. is described on the basis of three skulls and a lower jaw from the Lower Tertiary beds of the Ouled Abdoun phosphate basin, Morocco. It differs from A. cuneiceps, A. antiqua and A. athersuchi essentially in the frontal well retracted from the orbital margin, with a broad prefrontal/postorbital contact, a more developed secondary palate, and the anterior part of the lower jaw more dorsoventrally flattened, with a wider triturating surface and a longer symphysis, without lingual ridge. This is the first record of Argillochelys from Africa.

The structural/stratigraphic development of the Sishen South (Welgevonden) iron ore deposit, South Africa, as deduced from ground gravity data modelling

The Palaeoproterozoic Transvaal Supergroup in the northern Cape Province of South Africa hosts high grade (>60%Fe) hematitic and specularitic iron and manganese mineralisation. The mineralisation is primarily exposed along the western margin or in the central part of a major interference fold structure known as the Maremane dome. The bulk of South Africa's iron ore production is currently provided by two active mines, Kumba Resources megaton Sishen iron ore mine on the northern end of the dome, and the smaller Assmang Beeshoek mine on the southern closure. The undeveloped Sishen South deposit, which contains ∼400 Mt of high-grade hematite ore, is located ∼9 km towards the southwest of Postmasburg. It forms a linear extension of the Beeshoek mine and as such contains comparable laminated, breccia and conglomeratic iron mineralisation. The Transvaal Supergroup sediments were deposited in two distinct fault-controlled basins on the Archean Kaapvaal craton. Basement rocks in the western Griqualand West basin are formed by a carbonate platform sequence (Campbellrand Subgroup), which is overlain by a thick sequence of banded iron formation of the Asbesheuwels Subgroup. A major unconformity separates these rocks from the red-bed Gamagara Formation, which is correlated with the base of the Olifantshoek Supergroup. Diamictites and lavas of the Postmasburg Group have been thrust over these units from the west. The mineralisation process is related to regional scale supergene iron enrichment of Kuruman banded iron formations along the unconformity. During regional tectonism associated with the Kheis orogeny (2400–1700 Ma) the Maremane dome was uplifted, and the basal dolomite units thus exposed to erosion and karstification. The overlying banded iron formations collapsed into karst sinkhole structures where leaching of silica and enrichment of hematite occurred. Although the exact mechanism of the mineralising process remains unclear, karstification preserved components of the original concordant laminated and massive ores. These ores were subsequently eroded and deposited as conglomeratic and gritty ores down-dip of the Maremane dome in alluvial fan systems. A thin veneer of recent calcrete or Tertiary Kalahari clay beds masks the subsurface geology and most of the orebodies, thus ground geophysical gravity surveys proved excellent exploration tools to penetrate the surficial cover. These surveys were used extensively for delineation drilling and to deduce the subsurface geology and structural development of the area. Finally Sishen South orebodies were modelled with ModelVision software in an attempt to obtain an exploration template for the surrounding area.

Radial Resistivity/IP Surveys Using a Downhole Current Electrode

The sensitivity and resolution of surface resistivity and Induced Polarization (IP) surveys can be severely restricted by the conductivity and thickness of overburden material. Electrode arrays using a current electrode buried below the overburden can increase the sensitivity and resolution of surveys conducted in such environments. A current electrode is located down a drillhole, and resistivity and chargeability measurements are made on the surface along survey lines radial to the drillhole. Reconnaissance resistivity/IP surveys using the downhole radial electrode array were conducted in the Cambro-Ordovician Mt Windsor Volcanics near Charters Towers in Queensland, an area covered by electrically conductive unconsolidated sediments of the Late Tertiary Campaspe Beds. The surveys demonstrated the effectiveness of the array in detecting anomalies from buried base metal targets. Data were acquired from a number of surveys conducted around a series of adjacent drillholes to provide continuous coverage across the prospective area. The data from individual radial traverses show the sounding response of the ground as well as the ground response along the profile. A method was devised for removing the sounding response, which is local to each drillhole, from each radial traverse so that the data from each traverse could be merged to form a continuous data set. A number of issues have been identified for future research which include the optimum depth of the buried current electrode, removal of the sounding response, and interpretation of the survey data.

Bartholomew James Sulivan's discovery of fossil vertebrates in the Tertiary beds of Patagonia

While commanding a Royal Navy survey of the Falkland Islands in 1845, Bartholomew James Sulivan discovered and collected fossil mammals at Rio Gallegos, Patagonia. Described the following year by Richard Owen, Sulivan's specimens comprised the first collection taken from what would later be designated the Santa Cruz beds (early-middle Miocene), the most prolific fossil mammal horizon in South America and the oldest discovered by Sulivan's time. Unfortunately, Charles Darwin's conservative estimate of the age of the fossils delayed the full appreciation of Sulivan's discovery. Sulivan was only moderately successful at attracting interest in his discovery among British naturalists. By the time that the first extensive collections of Santa Cruz fossil mammals were made by Argentine paleontologists Carlos and Florentino Ameghino, in the 1890s, Sulivan's pioneering role in the history of South American vertebrate paleontology had been overshadowed and all but forgotten. An examination of Sulivan's experience provides a general model for the process whereby some contributors to science descend from initial fame to lasting obscurity.

Lithology of Tertiary beds in Kozjansko, Eastern Slovenia

Lithology of Tertiary beds in Kozjansko, Eastern Slovenia

Geology of a Major New Porphyry Copper Center in the Superior (Pioneer) District, Arizona

A new porphyry copper deposit has been discovered in the Superior (Pioneer) district of east-central Arizona, lying under thick Tertiary cover approximately 2 km south of the historic Magma vein. The porphyry center was encountered in the course of an exploration drilling campaign conducted from 1992 through 1997, comprising a series of subvertical surface core holes and subhorizontal underground core holes ranging in length from 1,000 to 1,955 m. The system is large, structurally intact, and shows indications of a substantial hypogene mineralized zone that averages between 1.0 and 2.0 percent Cu. The deposit is hosted by a thick sequence of Cretaceous (?) volcaniclastic and siliciclastic sedimentary rocks. The Mesozoic strata rest disconformably on calcareous units of the uppermost Paleozoic Naco Group and are intruded by an east-northeast–striking swarm of quartz porphyry dikes. The dike swarm is truncated at the basal Tertiary unconformity, under which the Mesozoic section is buried by 600 to 1,200 m of unmineralized overburden composed of the Oligocene-Miocene Whitetail Conglomerate and the Miocene (18.6 Ma) Apache Leap dacite tuff. The attitude of the basal Tertiary beds shows that the porphyry center has been tilted 30° to 35° to the east-northeast. A broad zone of hydrolytic alteration characterizes the high structural levels in Mesozoic wall rocks. Peripheral propylitic alteration in the volcaniclastic rocks is marked by epidote and chlorite, giving way inwardly to a narrow zone of chlorite-dominant alteration in which epidote is destabilized in favor of smectite clays and carbonate. This chlorite zone corresponds closely to the alteration type of Meyer and Hemley (1967). The propylitic fringe of the system is erratically mineralized by vein-controlled pyrite, sphalerite, and specularite with minor chalcopyrite and galena. Chloritic rocks in the intermediate argillic halo contain pyrite and chalcopyrite. The intermediate argillic alteration mantles an inner zone of pervasive quartz-sericite-pyrite. The sericitic zone is strongly pyritic, with bornite and lesser chalcopyrite. Within sericitically altered rock, pyrite-chalcocite-digenite-bornite veins exhibit centimeters- to meters-wide halos of advanced argillic alteration in which sericite is replaced by kaolin group clays. The quartz-sericite-pyrite zone is superimposed on earlier potassic alteration that remains preserved at deeper levels. The base of the Mesozoic sequence and shaly beds in the upper Naco Group section are pervaded with secondary biotite. Calcareous rocks in the Naco Group are altered to (1) pyroxene-epidote hornfelses and minor garnet-magnetite skarn, overprinted by (2) actinolite and (3) chlorite-carbonate-clay alteration. Biotitically altered rocks are mineralized by quartz-pyrite-chalcopyrite ± anhydrite veins. Molybdenite is present in an early generation of quartz-rich pyrite ± chalcopyrite veins. Hornfelses and skarn in the Naco Group are strongly mineralized by quartz-poor, chalcopyrite-pyrite-anhydrite veins with chloritic envelopes. Surface and underground drilling into the deposit has outlined a zone of >1.0 percent hypogene Cu that is at least 750 m long by 250 m wide by 300 m high, elongated to the east-northeast. The same volume of rock also averages 0.02 percent Mo and 2 ppm Ag. This zone apexes approximately 300 m below sea level, slightly more than 1.5 km below the ground surface, and remains open in all directions laterally and at depth. Four of the last five drill holes penetrating this zone ended in rock assaying >2.0 percent hypogene Cu.

Paragenèses silico-alumineuses précoces d'âge Quaternaire en contexte cryptokarstique (Haute-Normandie, France) ; implications pour l'argilogenèse

Abstract We describe a silico-aluminous paragenesis (halloysite, gibbsite, alumohydrocalcite) in weathered Tertiary beds trapped within Quaternary cryptokarstic structures (Normandy, France). This paragenesis was developed from gels neoformed in the immediate vicinity of carbonate levels that acted as neutralizers for (Si, Al)-rich acid solutions. The gels occur in millimetric to centimetric fissures. We refer to these neogeneses as to an early stage of the evolution that may lead to a complete transformation of gels into crystallized halloysite, gibbsite...

Hydrochemical trends, palaeorecharge and groundwater ages in the fissured Chalk aquifer of the London and Berkshire Basins, UK

The hydrochemical, radiochemical, stable isotope, 14C and dissolved noble gas composition of groundwaters has been determined along two profiles across the confined, fissured Chalk aquifer of the London Basin of southern England, and for selected sites in the adjacent Berkshire Basin. During downgradient flow in the London Basin aquifer, the groundwater chemistry is modified by water–rock interactions: congruent and incongruent reaction of the carbonate lithology resulting in enhanced Mg/Ca and Sr/Ca ratios and 13C contents with increased residence times; redox and ion exchange reactions; and towards the centre of the Basin, mixing with a residual saline connate water stored in the Chalk matrix. There is evidence from anomalous water chemistries for a component of vertical leakage from overlying Tertiary beds into the confined aquifer as a result of historical dewatering of the aquifer. Dissolved noble gas contents indicate the climate was up to 4.5°C cooler than at present during recharge of the waters now found in the centres of both Basins; stable isotope ( 2H and 18O) depletions correspond to this recharge temperature change. For evolved waters having δ 13C > −8‰ PDB a negative linear correlation is demonstrated between derived recharge temperatures and δ 13C values, which is interpreted as mixing between relatively warm, light isotopic, fracture-borne waters and cooler stored waters of the matrix having a 13C signature more or less equilibrated with the Chalk. From geochemical ( 14C, 4He) age estimates, the abstracted water is interpreted as being either of wholly Holocene/post-Devensian glacial origin, or an admixture of Holocene and Late Pleistocene pre-glacial (cold stage interstadial) recharge. Devensian pleniglacial stage waters of the Last Glacial Maximum are not represented.

Charles Darwin's field notes on the geology of Hobart Town- a modern appraisal

A transcription of unpublished field notes made by Charles Darwin details the observations and initial deductions he made on the geology of Hobart, Tasmania, and comments thereon place his work in a modern context. The field notes enable the routes of his excursions while in Hobart to be inferred in considerable detail and confirm earlier ideas about the site from which important fossils were collected. They also allow some appreciation of Darwin's style of geological study. Darwin's field notes reveal that he thought of the possibility of the influence of earthquakes on Tertiary beds at Sandy Bay. Several of his ideas on the geology, shown by these notes, some of them also in his publications (e.g. the origin of a Tertiary freshwater limestone, and relative movement of the land and sea in the area), remain topics for further study. His work in the Hobart area and his understanding of the geology of Van Diemen's Land were enhanced by contact with George Frankland, Surveyor-General, who had a long-term and systematic interest in the topic. The notes formed the basis ofa geological Memo on Hobart Town and, later, two publications, each work having a different purpose and emphasis. His work near Hobart did not produce enough information for the construction of a stratigraphic framework (imperfect sketches of the Geology). The imperfections, with other considerations, may have influenced him not to publish the memo which rendered subsequent publications less clear and less useful than had the memo been published. Darwin recognised the influence of glaciation on the Permian sedimentary rocks in the area but did not publish his observations and interpretation

14C Age of Glaciation in Estrecho De Magallanes–Bahía Inútil, Chile

Basal 14C dates from a core of the mire at Puerto del Hambre (53°36'21″S, 70°55'53″W), located within the area of glaciation in Estrecho de Magallanes–Bahía Inútil, Chile, are no older than 14,455 ± 115 yr BP. The 14C dates are on samples from which screening isolated autochthonous plant remains. Previous 14C dates of 15,800 ± 200, 16,590 ± 320, and 16,290 ± 140 yr BP are from bulk samples collected from similar basal increments at the site during 3 separate, independent coring operations. The previous suite of 14C dates was suspected to be contaminated by older carbon in the light of chronological evidence, which indicates a 14C age of approximately 14,850 yr BP for glaciation elsewhere in southern Chile. Contamination by “infinitely old” carbon reworked from nearby Tertiary beds and redeposited at Puerto del Hambre is evidently the cause for the older 14C dates.