Thesis (Ph. D.)--Durham University, 2004. / Includes bibliographical references (p. 117-127).

The concern of the investigation described in this thesis has been to examine certain drift deposits in southern Wiltshire and to consider their distribution in relation to the accepted interpretation of the landscape. The area examined has been discussed by Wooldridge and Linton (1955) but lies on the periphery of the tract with which they deal, and their treatment is essentially theoretical and not circumstantial. In the course of the investigations which are described, samples were collected from over two hundred sites, surface indications of the geology were examined at a substantially larger number of sites and more than thirty sections were specially excavated in particularly interesting locations. The work is based not on the application of refined geological techniques but on the ability to distinguish, in hand specimens, common and distinctive rocks. In important sections, samples of gravel of from 6 lbs to 2O lbs weight were secured and broken down into three fractions (¹⁄₁₆"-⁵⁄₃₂"; ⁵⁄₃₂"-¹⁄₂"; ¹⁄₂" upwards); for correlative purposes exact counts of the component materials were carried out for the two coarser fractions. Although some of the individual examples encountered are problematic the conclusions have invariably been based on a significant volume of unmistakable material. The use of refined correlative techniques to confirm the results has not been attempted. This omission to some extent reflects the nature of the investigation, which is best regarded as a reconnaissance of a large area, describing evidence not only in Wiltshire but on the Chalk and Eocene outcrops elsewhere in We ss ex, for the most part on ground lying to the West of the Salisbury Avon. The results of the work are described in a comparative study of landscape features using, so far as possible, the whole geographical context of the ground examined: the dissection and weathering of the surface, the drifts and soils which rest upon it, and the relation of the ground to relief both above and below it. In Part One of the thesis an attempt is made to establish the nature of the sub-Eocene unconformity. A study of the Pleistocene river gravels about Salisbury suggests that Eocene formations may have been preserved on the western part of Salisbury Plain at the beginning of the Pleistocene period. This result is inconsistent with the views adopted by Wooldridge and Linton. The composition of the gravels examined suggests that the Eocene formations in question did not resemble formations now recognised in the main Eocene outcrops adjoining Salisbury Plain. A study of the Palaeogene outlier on Salisbury Plain, at Clay Pit Hill, shows the gravels in the outlier to be closely similar in terms of petrology to the distinctive gravels in the Bagshot Beds about Dorchester in Dorset, and a correlation with these beds is suggested. A distinctive gravel from another Palaeogene outlier, at Cley Hill, near Warrninster, is described. This gravel at a height of about 800' O.D. appears to be preserved at or near the level of its original deposition, and is tentatively referred to the Oligocene period. The evidence at Cley Hill and Clay Pit Hill is taken to show that the Chalk suffered extensive erosion during the Eocene and Oligocene periods. A study of sites on the ground intervening between the Palaeogene outliers on Salisbury Plain and the Bagshot outcrop in Dorset provides new evidence on the nature of the Reading Beds, which tends to confirm the results of the investigations on Salisbury Plain. In Part Two of the thesis drifts on the mid- Tertiary surface of Wooldridge and Linton (1955) are described. Drifts on the Upper Greensand outcrop in the Vales of Wardour and Warminster are believed to be of periglacial origin and Pleistocene age. Drift on the Portland outcrop in the Vale of Wardour appears to be the debris of Lower Cretaceous formations and probably rests on an intra-Cretaceous surface. On the Chalk a contrast is discerned between ground occupied by deep very flinty drifts of residual aspect and ground occupied by shallower flint drifts, also of residual aspect. The shallow drifts are shown to be associated with the relics of gravels incorporating Upper Greensand, Lower Cretaceous and Jurassic debris. The deep very flinty drifts are believed to confirm the views of Wooldridge and Linton concerning the mid-Tertiary surface, but the shallower drifts and associated gravels are thought to rest on a separate surface, and the Cretaceous and Jurassic debris is believed to imply the competence of transverse gradients during the dissection of the mid-Tertiary surface. The evidence described in Part Two of the thesis is difficult to reconcile with the concept of marine transgression across the Wiltshire Chalk. In Part Three of the thesis drifts on the supposed marine plain are described and the marine origin of the surface is rejected. Specific evidence of a 'Pliocene' transgression in Wessex is reviewed and a study of supposed 'Pliocene' material refers the material in question to the Eocene period. Problematic aspects of Pliocene stratigraphy and the concept of superimposition from a Pliocene surface are reviewed. Pinchemel's objections (1954) to a depositional surface are accepted but his views on fluvial aggradation are rejected in a study of gravel at Alderbury, near Salisbury, referred by him to this aggradation. Difficulties inherent in the concept of marine planation are recognised and ground referred by Wooldridge and Linton to the Pliocene marine plain is shown to be essentially indistinguishable from their mid-Tertiary surface and is therefore believed to be correlative with it. This view implies post-mid-Tertiary deformation of the Chalk. In Part Four of the thesis a theory of drainage evolution is developed to replace the hypothesis based on a concept of late Tertiary marine planation. Drifts, landforms and drainage morphology in the Vale of Wardour are shown to demonstrate a deformed, subaerial planation surface, bevelling the outcrop of the Chalk and earlier formations at a level below the mid-Tertiary surface of Wooldridge and Linton. The present drainage pattern is believed to have originated during the deformation of this surface, probably in the Plio-Pleistocene interval. This subaerial surface is also identified on Salisbury Plain and the origin of the drainage pattern there and in the Alderbury syncline is described. The available evidence suggests that the subaerial surface was elaborated during the Pliocene period following the deformation of the Oligo-Miocene (mid-Tertiary) surface. The character of the late Tertiary (Pliocene) surface suggests comparisons with the surfaces described by King (1962) and termed by him pediplains, although the nature of the process involved remains doubtful. In Part Five of the thesis some aspects of Pleistocene erosion are treated. Adjustments to the drainage pattern in the basin of the Avon above Salisbury during the Pleistocene period are discussed. This account is based on analyses of gravels of the Avon and its tributaries about Salisbury. The concept of successive stages of marine planation in the Hampshire Basin daring the Pleistocene period is rejected in a study of the composition and morphology of the Pleistocene gravels. An alternative scheme of subaerial planation is suggested and some morphological evidence of this planation on the Wiltshire Chalk and on the Eocene outcrop in the Hampshire Basin is described. The problems of scarp recession and the dessication of the dry valleys are reviewed and the concept of scarp recession is abandoned.

No description available.

No description available.

No description available.

Texte remanié de: Doctoral thesis--Durham university, 2004. Titre de soutenance : Landscape, settlement and society : Wiltshire in the first millenium AD. / Bibliogr. p. 117-127.

The problem of relative spacecraft motion estimation is considered with application to various reference and relative orbits. Mean circular and elliptic orbits are analyzed, with relative orbits ranging in size from 1 km to 10 km. Estimators are built for three propagation models: (i) Gim-Alfriend State Transition Matrix, (ii) the J2-Linearized Equations of Motion for Circular Orbits, and (iii) the Clohessy-Wiltshire Equations of Motion. Two alternative models were developed in an attempt to ac- count for unmodeled nonlinearities: (i) Biased Clohessy-Whiltshire Equations, and (ii) J2 -Linearized State Transition Matrix. Two estimation techniques are presented in an attempt to explore and determine which propagation model minimizes the error residual: the linear Kalman filter is presented under the assumption of vector based, GPS-type measurements; the extended Kalman filter is analyzed assuming angle-range, optical-type measurements. Sampling time is varied to look at the effect of measurement frequency. It is assumed that the orbit of one of the satellites, the chief, is known reasonably well. This work showed that the error residuals from the state estimates were minimized when the propagation technique utilized was the Gim-Alfriend State Transition Matrix. This supports conclusions that are obtained outside of the estimation problem. Additionally, the error residuals obtained when the propagation technique was the Clohessy-Wiltshire Equations is comparable to the more complicated models. Unmodeled nonlinearities affect the magnitude of the error residuals. As expected, the Gim-Alfriend STM comes closest to the truth; for smaller eccentricities (0.005), the Clohessy-Wiltshire EOM show minor deviations from the truth. As the eccentricity increases, the linear models begin to diverge greatly from the true response. The additional two models (the biased CW equations, and the linear STM) show decent performance under specific conditions. The former accounts for some of the unaccounted for nonlinearities. The latter exhibits comparable performance to the Gim-Alfrien STM for circular reference orbits. However, in each case, as the nonlinearity of the problem increases, the accuracy of the model decreases.

no / During the micro-excavation of the cauldrons, residues were identified which appeared different from the surrounding soil and metal corrosion products. Thirty-seven of these residues from nine cauldrons and two significant fragments of incomplete cauldrons were analysed by gas chromatography-mass spectrometry (GC-MS) along with two samples of soil from the micro-excavation for comparison. The aim of the analysis was to determine whether these residues contained any organic material related to the use of the cauldrons, specifically lipids (fats, waxes, resins etc.) from the preparation of food or drink. Two of the samples from the cauldrons were also sent for compound specific carbon stable isotope analysis by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) to give a more precise identification of the residues.