The Symap Programme for Computer Mapping

Robertson, Jenny

doi:10.1179/000870467786937684

Cited by 6 publications

(3 citation statements)

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“…In all instances, the variation between the values at different grid points was significantly greater at the 99.9% level than the variation within the samples at a single point (table 4). (Robertson 1967) was used to describe the magnitude and distribution of lithological properties for the whole set of samples which had been sub jectively assigned in the field to the Calcethorpe, W ragby and Lowestoft Tills, the M arly Drift, the Third Cromer Till and the Norwich Brickearth (table 3 and figure 5). This technique uses a two dimensional interpolation function designed for irregularly spaced data.…”

Section: (D) Tests O F Representativenessmentioning

confidence: 99%

The distribution, variation and origins of pre-Devensian tills in eastern England

Perrin

Rose

Davies

1979

Phil. Trans. R. Soc. Lond. B

126

113

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In order to define quantitatively the lithological properties of the pre-Devensian tills in eastern England, calcium carbonate contents and mechanical compositions of 501 samples from 289 sites have been measured and heavy minerals counted in 102 of them. The results show that the tills may be divided into two groups: ( a ) a North Sea Drift group consisting of the Norwich Brickearth, the Cromer Tills, the Marly Drift of Cromer type and till members of the Contorted Drift, which is characterized by high sand and low opaque heavy mineral contents; and ( b ) a Lowestoft Till group including the Lowestoft Till of East Anglia, the Chalky Boulder Clay of the east Midlands, the Calcethorpe and Wragby Tills and the Lowestoft-type Marly Drift, which is characterized by low sand and high opaque values. The qualitative similarity of the mineral suites in the two groups, however, suggests a common origin in the North Sea basin. Automated contouring (SYMAP) has been used to represent the spatial distribution of till properties. These confirm that the Lowestoft Till group can be spatially separated from the North Sea Drift group, and divided into a Calcethorpe-Marly facies high in carbonates and lying astride the Wash, and a Lowestoft-Wragby facies with moderate but variable contents of calcium carbonate and occupying the rest of the region. Trend surface analysis has been applied to the Lowestoft Till group. At the first order level there are decreasing trends across the region, from northeast to southwest, in calcium carbonate, amphibole and epidote values and increasing trends in silt and clay. These are interpreted as showing a general movement from the North Sea of sandy and chalky material which became progressively modified by assimilation of Mesozoic clays. Higher order surfaces, particularly those of sand, garnet and amphibole values, point to the Wash as the focus of this glacial activity. It is proposed that the most vigorous stream of ice entered eastern England at this point, levelling the Cretaceous scarps and excavating the Jurassic clays of the Wash-Fens basin, and then fanned out into most of the region to deposit the clay-rich Lowestoft-Wragby facies. The Calcethorpe-Marly facies is considered to represent chalky North Sea material carried by marginal, and weaker, ice streams directly onto the Chalk of Lincolnshire and north Norfolk. The North Sea Drift group is believed to be the product of another ice body, penecontemporaneous with that depositing the Lowestoft group, which entered Norfolk from a more easterly part of the North Sea, incorporating sediments from this basin, but without crossing substantial outcrops of Jurassic or Lower Cretaceous formations or Tertiary clays. The Marly Drift includes a variant showing lithological affinities with both Lowestoft and Cromer Tills and which may be the product of complex interaction between the two ice sheets. All the tills studied seem most likely to be of Anglian age.

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Section: (D) Tests O F Representativenessmentioning

confidence: 99%

The distribution, variation and origins of pre-Devensian tills in eastern England

Perrin

Rose

Davies

1979

Phil. Trans. R. Soc. Lond. B

126

113

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“…The extension of point referencing to produce chorographic maps also lies at the heart of Symap (Robertson 1967, Rosing 1969). This is a more widely advanced technique which builds up composite patterns through assigning or interpolating data values and representative symbols around selected control points, normally the centroids of areas.…”

Section: Chorographic Map Routinesmentioning

confidence: 97%

Computer graphic techniques in planning

Davies

1970

Planning Outlook

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“…Meanwhile, another important milestone in the development of GIS is a series of developments made at the Harvard Laboratory still in the 1960s. This lab has been pioneer in the implementation of several GIS software packages such as SYMAP (Robertson 1967) and POLYVRT (see Peucker and Chrisman 1975) and in the design of geographical data structures and formats such as TIGER and DIME (Chrisman 1988). These spatial data structures played a significant role that enforced layered architectures in GIS databases and extended their impacts on temporal GIS development.…”

Section: Introductionmentioning

confidence: 99%

A Survey of Modelling Trends in Temporal GIS

et al. 2018

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The main achievements of spatio-temporal modelling in the field of Geographic Information Science that spans over the past three decades are surveyed. This article offers an overview of: (i) the origins and history of Temporal Geographic Information Systems (T-GIS); (ii) relevant spatio-temporal data models proposed; (iii) the evolution of spatio-temporal modelling trends; and (iv) an analysis of the future trends and developments in T-GIS. It also presents some current theories and concepts that have emerged from the research performed, as well as a summary of the current progress and the upcoming challenges and potential research directions for T-GIS. One relevant result of this survey is the proposed taxonomy of spatiotemporal modelling trends, which classifies 186 modelling proposals surveyed from more than 1450 articles. CCS Concepts: • Information systems~Geographic information systems • Information systems~Temporal data • Computing methodologies~Spatial and physical reasoning • Computing methodologies~Temporal reasoning Additional Key Words and Phrases: spatio-temporal models; survey; literature review; temporal GIS; time geography; spatio-temporal databases; temporal models.

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The Symap Programme for Computer Mapping

Cited by 6 publications

References 0 publications

The distribution, variation and origins of pre-Devensian tills in eastern England

The distribution, variation and origins of pre-Devensian tills in eastern England

Computer graphic techniques in planning

A Survey of Modelling Trends in Temporal GIS

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