Geological Age of the Claypool Site, Northeastern Colorado

1960 ◽  
Vol 26 (2) ◽  
pp. 236-243 ◽  
Author(s):  
Harold E. Malde
Keyword(s):  
Climatic Changes ◽  
Coarse Sand ◽  
Physical Characteristics ◽  
Washington County ◽  
Brown Soil ◽  
Geological Age ◽  
Thermal Maximum ◽  
Cody Complex ◽  
Fine Gravel ◽  
Eolian Deposit

AbstractArtifacts related to the Cody complex occur in medium-grained sand that is spread as a blanket eolian deposit a few feet thick in the Claypool site area, Washington County, Colorado. The artifact-bearing sand lacks noticeable dunal topography and lies unconformably on marl of Yarmouth age and on waterlaid coarse sand and fine gravel of Kansan age that underlie the marl. The deposits underlying the artifact-bearing sand are much too old to date the artifacts precisely, but the physical characteristics of the artifact-bearing sand suggest that it was deposited under conditions cool and dry, rather than warm and dry, possibly during retreat of Valders ice that began about 10,000 years ago. A moderately mature Brown Soil about 5 feet thick developed on the sand, possibly about 7000 to 5000 years ago during a moist phase of the Thermal Maximum. Thus, the artifacts are possibly 10,000 to 7000 years old. Deposits which overlie the artifact-bearing sand reflect several episodes of erosion and sedimentation that are inferred to represent climatic changes.

scholarly journals The Propagation of Guavas from Stem Cuttings

1969 ◽  
Vol 47 (4) ◽  
pp. 280-289
Author(s):  
W. Pennock ◽  
G. Maldonado
Keyword(s):  
Acid Treatment ◽  
Coarse Sand ◽  
Appreciable Effect ◽  
Stem Cuttings ◽  
High Susceptibility ◽  
High Concentration ◽  
Indolebutyric Acid ◽  
Anthracnose Disease ◽  
Rooting Media ◽  
Fine Gravel

1. A highly successful propagation method is described by which hundreds of side-sprouts are first induced on the parent guava tree. These are later cut and rooted under alternatmg mist, with leaves attached. By using this method it is possible to produce from 500 to 1,000 guava plants from a single 3-year-old tree within 10 months. 2. An experiment is also described and discussed which showed that different rooting media, such as coarse sand and very fine gravel, with Coco-peat, fir bark, Vermiculite, Perlite, and Mexifern, had no appreciable effect on rooting. But treatment with a relatively high concentration, 200 p.p.m., of indolebutyric acid improved and accelerated rooting markedly. Rooting was still further improved if 2 percent of sugar was combined with the indolebutyric acid treatment. 3. The high susceptibility of cuttings under mist to anthracnose disease is mentioned and the usual course of the disease described. Recommendations are suggested for reducing the incidence of this disease.

The Claypool Site: A Cody Complex Site in Northeastern Colorado

1960 ◽  
Vol 26 (2) ◽  
pp. 223-235 ◽  
Author(s):  
Herbert W. Dick ◽  
Bert Mountain
Keyword(s):  
Geological Age ◽  
Sand Deposit ◽  
Cody Complex

AbstractEden and Scottsbluff points and Cody knives were found in situ in a sand deposit with an estimated geological age of 10,000 to 7000 years. Numerous other Cody complex artifacts from the surface of the site are described. Fragmentary remains of a mammoth in a marl bed are stratigraphically older than the Cody artifacts.

scholarly journals Road deposited sediment: implications for the performance of filter drains servicing strategic trunk roads

2019 ◽  
Vol 80 (4) ◽  
pp. 747-761
Author(s):  
Ged Mitchell ◽  
Kehinde Oduyemi ◽  
Joseph Akunna
Keyword(s):  
Grain Size ◽  
Asset Management ◽  
Size Fraction ◽  
Coarse Sand ◽  
The Road ◽  
Large Particles ◽  
Trunk Road ◽  
Total Particle ◽  
Instantaneous Values ◽  
Fine Gravel

Abstract This study investigates the contribution of road deposited sediment (RDS) to clogging and the operational lifecycle of highway filter drains (HFDs). RDS samples were collected from nine Scottish trunk roads and fractionated into grain size classes to determine their particle size distributions (PSDs). Results show that RDS PSDs, and the percentage of each grain size fraction, are highly variable. However, despite being collected from different trunk roads, PSD trends are similar, with individual RDS particles ranging in size from <63 μm to >10,000 μm. Medium sand, coarse sand, fine gravel and medium gravel make up 84.1% of the total particle mass concentration, with particles >1,000 μm mostly mineral or asphalt. The study also reveals that the dynamic nature of a trunk road catchment dictates that grading envelopes are essentially instantaneous values. These findings indicate that large particles from the road surface contribute to clogging and have the potential to reduce the operational lifecycle of HFDs. The study also demonstrated that assuming a single RDS PSD profile for filter drain asset management purposes is unlikely to be representative of a trunk road catchment profile.

Fossil coleopteran assemblages as sensitive indicators of climatic changes during the Devensian (Last) cold stage

1977 ◽  
Vol 280 (972) ◽  
pp. 313-340 ◽  
Keyword(s):  
Thermal Environment ◽  
Climatic Changes ◽  
Cold Period ◽  
Ocean Bottom ◽  
Moderate Degree ◽  
Oceanic Circulation ◽  
Insect Fauna ◽  
Climatic Fluctuations ◽  
Thermal Maximum ◽  
Asiatic Species

Goleoptera are abundant fossils in Quaternary deposits laid down under freshwater or terrestrial conditions. They display a remarkable degree of evolutionary stability and reasons are adduced for believing that this morphological constancy is associated with physiological constancy. Thus whole communities of species have been assembled in the past, drawn together by common ecological preferences, so that the species composition of fossil assemblages resembles that of modern faunas. Marked changes in the geographical distribution of Coleoptera during the last glacial-interglacial cycle conform to an orderly pattern of climatic fluctuations. The Coleoptera contribute most information about the Devensian climates during warmer interstadial periods because during the colder episodes conditions in Britain became more or less intolerable to insect life and the fossil content of the sediments approaches zero. The term interstadial is here used for an interlude of milder climate in an otherwise cold period which either does not attain temperatures equivalent to those of the present day or which attains temperatures as warm, or even warmer than those of today but which does not last long enough for floral and faunal equilibrium to become established. During the Ghelford Interstadial, at the limit of acceptable radiocarbon dating but possibly about 60000 years (a) ago, the climate in central Britain was rather cooler than now with a moderate degree of continentality. The Upton Warren Interstadial complex, between about 45000 and 25000 a ago, reached its thermal maximum at about 43000 a before present when temperatures were rather higher than those of the present day and the climate was moderately oceanic. This episode may have been as short in duration as 1000 a. After this the interstadial is characterized by a period of much lower temperatures, with a greatly increased degree of climatic continentality, lasting for about 15 000 a. Few insect faunas are known from the period of maximum ice expansion but the scant evidence supports an interpretation of a climate of arctic severity. During the closing phases of the Devensian cold period there is faunal evidence for only one major climatic oscillation - here called the Windermere Interstadial. The sharp rise in the thermal environment at its beginning took place rather before 13000 a ago but later than 14000 a ago. Thermal maximum was attained almost immediately with temperatures during the summer at or above their present day level. Moderate oceanicity of the climate at this time means that winter temperatures were not much lower than those of the present day. At least during the earliest parts of this interstadial a temperate insect fauna was associated with a flora almost entirely dominated by herbs. The decline of the Windermere Interstadial from its thermal maximum seems to have been more or less synchronous from southern to northern England and to have taken place at about 12 200 a ago. A cool temperate phase then ensued for over one thousand years with summers about 3 °G cooler than during the thermal maximum. This episode corresponds in time to the Allerod oscillation. The Loch Lomond Stadial between 11000 and 10000 a ago saw the return of arctic faunas to the British Isles even as far south as Cornwall. The presence of Asiatic species, though not abundant, suggests that the climate at this time may have been rather continental. The timing and intensity of the climatic changes during deglaciation show close parallelism to the changes in oceanic circulation in the eastern Atlantic now being interpreted from cores of ocean bottom sediments.

Notes On molluscan meiofauna from Plymouth

1984 ◽  
Vol 64 (3) ◽  
pp. 497-502 ◽  
Author(s):  
Luitfried V. Salvini-Plawen
Keyword(s):  
Personal Communication ◽  
First Record ◽  
Coarse Sand ◽  
Marine Biological Association ◽  
Preliminary Examination ◽  
Marine Sand ◽  
Two Samples ◽  
Interstitial Fauna ◽  
First Time ◽  
Fine Gravel

Preliminary examination of marine meiofauna from the Plymouth area, especially on mesopsammic representatives, resulted in the finding of several typically interstitial Mollusca. Among them, Caecum glabrum, Hedylopsis spiculifera, and Philinoglossa praelongata were recorded live for the first time in the area. This is also the first record of Ph. praelongata outside the Mediterranean Sea.During a short stay at the Marine Biological Association Laboratory some preliminary studies on meiofauna were made. To obtain information especially about the interstitial fauna of marine sand, three typical samples of coarse sediment from different positions were examined.Sample A: Plymouth Sound, Outer Cawsand Bay, Queens Ground, 50°20' 03“ N, 4° 10' 27” W; ca. 6 fathoms (=11 m); coarse sand, about 6 1 examined (14 September 1982).Sample B: Plymouth Sound, southwest of Drake Island, 50° 21' 06“ N, 4° 09' 50” W; ca. 7 fathoms (= 13 m); coarse shell-sand, about 1 1 examined (15 September 1982).Sample C: outer Plymouth Sound, 50° 18' 51“ N, 4° 10' 30” W; ca. 12 fathoms (– 22 m); fine gravel, about 1 1 examined (15 September 1982).In this contribution only the gastropods are dealt with; other meiofauna will be treated ina later communication. The sole previous report of mesopsammic fauna from the Plymouth area is that of Spooner (1959). He examined two samples, one of which (Plymouth Sound) was taken fairlyclose to the above sample A, about 18“ more to the West at 4–5–5–5 fathoms (8–10 m; G. R. Forster, personal communication).

scholarly journals Multiple early Eocene carbon isotope excursions associated with environmental changes in the Dieppe-Hampshire Basin (NW Europe)

2020 ◽  
Vol 191 ◽  
pp. 33
Author(s):  
Sylvain Garel ◽  
Christian Dupuis ◽  
Florence Quesnel ◽  
Jérémy Jacob ◽  
Johan Yans ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Environmental Changes ◽  
Climatic Changes ◽  
Coastal Sediments ◽  
Carbonate Dissolution ◽  
Early Eocene ◽  
Higher Plant ◽  
Carbon Isotopic ◽  
Paleoclimatic Changes ◽  
Thermal Maximum

The early Eocene experienced a series of short-lived global warming events, known as hyperthermals, associated with negative carbon isotope excursions (CIE). The Paleocene-Eocene Thermal Maximum (PETM or ETM-1) and Eocene Thermal Maximum 2 (ETM-2) are the two main events of this Epoch, both marked by massive sea-floor carbonate dissolution. Their timing, amplitude and impacts are rather well documented, but CIEs with lower amplitudes also associated with carbonate dissolution are still poorly studied (e.g. events E1 to H1), especially in the terrestrial realm where hiatus/disconformities and various sedimentary rates in a single succession may complicate the assignation to global isotopic events. Here we present a new high-resolution multi-proxy study on the terrestrial, lagoonal and shallow marine late Paleocene-early Eocene succession from two sites of the Cap d’Ailly area in the Dieppe-Hampshire Basin (Normandy, France). Carbon isotope data (δ13C) on bulk organic matter and higher-plant derived n-alkanes, and K-Ar ages on authigenic glauconite were determined to provide a stratigraphic framework. Palynofacies, distribution and hydrogen isotope values (δ2H) of higher-plant derived n-alkanes allowed us to unravel paleoenvironmental and paleoclimatic changes. In coastal sediments of the Cap d’Ailly area, δ13C values revealed two main negative CIEs, from base to top CIE1 and CIE2, and 3 less pronounced negative excursions older than the NP11 nannofossil biozone. While the CIE1 is clearly linked with the PETM initiation, the CIE2 could either correspond to 1) a second excursion within the PETM interval caused by strong local environmental changes or 2) a global carbon isotopic event that occurred between the PETM and ETM-2. Paleoenvironmental data indicated that both main CIEs were associated with dramatic changes such as eutrophication, algal and/or dinoflagellate blooms along with paleohydrological variations and an increase in seasonality. They revealed that the intervals immediately below these CIEs are also marked by environmental and climatic changes. Thus, this study shows either 1) a PETM marked by at least two distinct intervals of strong environmental and climatic changes or 2) at least one “minor” CIE: E1, E2, F or G, was associated with strong environmental and climatic changes similar to those that occurred during the PETM.

scholarly journals A preliminary phylogeny and review of the genus Tasmanitachoides, with descriptions of two new species (Coleoptera, Carabidae, Bembidarenini)

ZooKeys ◽  
2021 ◽  
Vol 1044 ◽  
pp. 153-196
Author(s):  
David R. Maddison ◽  
Nick Porch
Keyword(s):  
New Species ◽  
Water Samples ◽  
Group Identification ◽  
Coarse Sand ◽  
Phylogenetic Hypothesis ◽  
Undescribed Species ◽  
Australian Capital Territory ◽  
Southeastern Australia ◽  
Two New Species ◽  
Fine Gravel

The genus Tasmanitachoides Erwin, a genus of very small carabid beetle endemic to Australia, is reviewed. Although uncommon in collections, they can be abundant and diverse on banks of fine gravel or coarse sand next to bodies of fresh water; samples from southeastern Australia suggest numerous undescribed species. An initial phylogenetic hypothesis for the genus is presented, including 19 of the 32 known species. The inferred phylogeny, based upon one mitochondrial and four nuclear genes, shows the kingi group to be sister to remaining Tasmanitachoides, with the wattsensis group and T. lutus (Darlington) also being phylogenetically isolated. Two new species are described: T. baehrisp. nov., from the Australian Capital Territory, is a member of the kingi group; T. erwinisp. nov., from Tasmania, is a member of the wattsensis group. Identification tools for described and some undescribed species are presented, including photographs of all known species.

New Record of Liocarcinus Mcleayi (Barnard, 1947), New Combination (Decapoda, Brachyura, Portunidae) From South Europe

Crustaceana ◽  
1996 ◽  
Vol 69 (1) ◽  
pp. 84-93 ◽  
Author(s):  
J. Enrique Garcia Raso ◽  
E. Manjón-Cabeza
Keyword(s):  
New Record ◽  
Anatomical Study ◽  
Coarse Sand ◽  
Southern Spain ◽  
New Combination ◽  
Brachyuran Crab ◽  
Bottom Currents ◽  
Fine Gravel ◽  
South Europe

AbstractFour specimens of the brachyuran crab Liocarcinus mcleayi (Barnard, 1947) (new combination), were captured from the Cadiz littoral (southern Spain) on a substratum of coarse sand and fine gravel under bottom currents at depths of 13 to 24 m. These captures represent a new record of this species from Iberian and European waters and support the known African influence in the Spanish littoral of Cadiz. Based on an anatomical study, a new combination is proposed for the name of the species.

Nearly pure sorting waves and formation of bedload sheets

1996 ◽  
Vol 312 ◽  
pp. 253-278 ◽  
Author(s):  
Giovanni Seminara ◽  
Marco Colombini ◽  
Gary Parker
Keyword(s):  
Grain Size ◽  
Small Amplitude ◽  
Mathematical Problem ◽  
Fluid Motion ◽  
Integral Condition ◽  
Turbulent Channel Flow ◽  
Coarse Sand ◽  
Bedload Transport ◽  
Grain Sorting ◽  
Fine Gravel

Bedload sheets are coherent migrating patterns of bed material recently observed both in flume studies and in field streams with beds of coarse sand and fine gravel. This newly recognized feature is inherently associated with the heterogeneous character of the sediment and consists of sorting waves with distinct coarse fronts only one or two coarse grains high.The question of the formation of bedload sheets poses an interesting and peculiar stability problem for the grain size distribution. Sorting waves are essentially two-dimensional migrating perturbations associated with variations of this distribution. We show that their growth is strictly associated with grain sorting. In fact the latter gives rise to perturbations of bedload transport which drive small perturbations of bottom elevation the amplitude of which scales with grain size. The sorting wave also induces spatial variations of bottom roughness, and consequently alters the fluid motion, which conversely exerts a spatially varying stress on the bed. The feature of bedload sheets which allows them to be distinguished from dunes over beds with coarse sand or fine gravel is then the fact that sorting is the dominant effect controlling their growth, rather than being a relatively small perturbation of the mechanism which gives rise to dunes in the case of uniform sediment.The requirement that perturbations should not alter the sediment budget leads to an integral condition which gives rise to an integro-differential mathematical problem. With the help of recently developed bedload relationships suitable for mixtures, as well as appropriate modelling of turbulent channel flow over a bed with spatially periodic perturbations of bottom elevation and roughness we are able to derive a general dispersion relation which can be readily solved in terms of undisturbed size densities in the form of sums of Dirac distributions.Perturbations are found to be unstable within a range of wavenumbers depending on the relative roughness and Froude number. We show that when the effects of perturbations of bottom elevation are neglected the unstable region corresponds to the range of conditions where the bottom stress leads bottom roughness, a range distinct from that which characterizes the formation of dunes. This result is given a physical explanation which depends crucially on the deviation from equal mobility of different grain sizes in the surface layer. The effect of perturbations of bottom elevation is however not negligible when the bottom roughness is fairly large compared to depth. In the latter case perturbations of bottom elevation and of bottom roughness are equally important, and gravel sheets are not easily distinguished from small-amplitude dunes.Comparison with the field observations of Whiting et al. (1985, 1988) is satisfactory insofar as the bedload sheet mode is unstable under the conditions of the experiments, and the predicted wavelengths fall within the experimental range. The laboratory observations of Kuhnle & Southard (1988), on the other hand, appear to fall within a range of bottom roughness where the observed bedforms do not exhibit features unambiguously distinct from those of small-amplitude dunes.

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