The land conservation conundrum of eastern barbados

Annals of the Association of American Geographers

Volumn 67, Issue 2, 1977, Pages 185-203

  Carson, M A ^a   Tam, S W ^b  

^a MCGILL UNIVERSITY   (Canada)

^b CHINESE UNIVERSITY OF HONG KONG   (Hong Kong)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 84972834729     PISSN: 00045608     EISSN: 14678306     Source Type: Journal    
DOI: 10.1111/j.1467-8306.1977.tb01132.x     Document Type: Article

References (29)

1. J. F. Lirios, “Rainfall Intensity-duration-frequency Maps for Barbados, West Indies,” internal report, Caribbean Meteorological Institute, November, 1971, 70 pp. The Haggatts data are based on 1964-1970 rainfall records.
2. The natural vegetation of Barbados has been described by D. Watts, “Man's Influence on the Vegetation of Barbados, 1627 to 1800,” Occasional Paper in Geography, No. 4, University of Hull, 1966, pp. 27-34.
3. R. K. Matthews, “Relative Elevation of Late Pleistocene High Sea Level Stands: Barbados Uplift Rates and their Implications,” Quaternary Research, Vol. 3 (1973), pp. 147-53.
4. The geology of the Scotland District has been described by A. Senn, “Geological Investigation of the Groundwater Resources of Barbados,” internal report of the British Union Oil Co. 1946, 110 pp. Interpretation of the Oceanic Formation, which occupies a stratigraphic position between the Joe's River Muds (Eocene) and the Coral Formation, is still fraught with difficulty, but the Formation is assumed to have covered the entire area under study here. Outliers of the Formation form the high points of the western and northern drainage divide, as well as underlying the Coral Formation of the southern divide (Fig. 3). The deposit upon which the 65 m knickpoint is located (location B in Fig. 3) was previously mapped as soils from the Oceanic Formation, but is interpreted by us as an extension of the conspicuous Coral-Oceanic colluvial lobe evident on the eastern end of the southern side of the basin.
5. S. W. Tarn, “Mechanisms and Spatial Patterns of Erosion and Instability in the Joe's River Basin, Barbados,” unpublished doctoral dissertation, McGill University, June 1975, 211 pp. Recent captures, between 1951 and 1968, may be found on aerial photographs.
6. The Mohr-Coulomb “friction” angle is also known as the angle of shearing resistance. In simple terms, it is analogous to the arctangent of the coefficient of friction of the material. The reader who is unfamiliar with this topic is directed to articles by A. W. Skempton and A. W. Bishop, “The Measurement of the Shear Strength of Soils,” Geotechnique, Vol. 2 (1950), pp. 90-108
7. A. W. Skempton, “The Long-Term Stability of Clay Slopes,” Geotechnique, Vol. 14 (1964), pp. 75-102. The prime superscript indicates reference to effective stress conditions, and the subscript r denotes reference to residual strength. The tests were undertaken in a conventional 6 cm square box, on samples approximately 3.3 cm thick, using applied pressures normal to the failure plane corresponding to those at shallow depths in the field, i.e. in the range 0-4 t m~2. All samples were saturated and sheared sufficiently slowly (0.07 cm day-1) to ensure zero pore pressures.
8. The term “quaquaversal” refers to strata dipping outward in all directions from a central point as a dome. This interpretation of the structural geology of the basement rocks is taken from S. N. Daviess, “Barbados: A Major Submarine Gravity Slide,” Bulletin, Geological Society of America, Vol. 82 (1971), pp. 2593-602.
9. Senn, op. cit. footnote 4.
10. The mechanism of undrained loading was discussed by J. N. Hutchinson and R. K. Bhandari, “Undrained Loading, A Fundamental Mechanism of Mud-flows and Other Mass Movements,” Geotechnique, Vol. 21 (1971), pp. 353-58.
11. K. C. Vernon and D. M. Carroll, “Soil and Land Use Surveys, No. 18, Barbados,” Soil and Land Use Section of the Regional Research Centre, Imperial College of Tropical Agriculture, University of the West Indies, Trinidad, March, 1965, 39 pp.
12. Cation exchange capacity was determined by ammonium saturation at a pH of 7.0 following the method described by H. D. Chapman, “Cation Exchange Capacity,” in Methods of Soil Analysis, Part 2 (edited by C. A. Black), American Society of Agronomy, Inc. 1965, pp. 891-901.
13. The “activity” of a sediment is defined as the quotient of the plasticity index and the percentage of the sediment, by weight, finer than 0.002 mm. A discussion of activity and the Atterberg limits of sediments is provided by R. E. Grim, Applied Clay Mineralogy (New York: McGraw-Hill, 1963), pp. 204-77.
14. D. G. Moore, “Shear Strength and Related Properties of Sediments from Experimental Mohole (Guadeloupe site),” Journal of Geophysical Research, Vol. 69 (1964), pp. 4271-91
15. A. J. Silva and C. D.Hollister, “Geotechnical Properties of Ocean Sediments Recovered with Giant Piston Corer, 1. Gulf of Maine,” Journal of Geophysical Research, Vol. 78 (1973), pp. 3597-616.
16. The use of the liquidity index as a discriminant between slip- and flow-type mass movements is illustrated more fully in M. A. Carson, “Mass-Wasting, Slope Development and Climate,” in E. Derbyshire, ed. Geomorphology and Climate (New York: John Wiley and Sons, 1976), pp. 101-36.
17. A. W. Skempton and F. A. Delory, “Stability of Natural Slopes in London Clay,” Proceedings, Fourth International Conference on Soil Mechanics and Foundation Engineering (Vol. 2) 1975, pp. 378-81. For readers who are unfamiliar with slope stability analysis and the principle of effective stress, it may be helpful to view the porewater pressures under a regolith as a consequence of “immersion” of the regolith in the groundwater system. The pore pressures thus combine to produce a buoyant force which reduces the effective weight of the regolith (and its component normal to a potential slip surface) and thus, also, the amount of frictional resistance which can be mustered.
18. Skempton, op. cit. footnote 7.
19. M. A. Carson, “Threshold and Characteristic Angles of Straight Slopes,” in Proceedings, Fourth Guelph Symposium on Geomorphology, in Press.
20. Senn, op. cit. footnote 4.
21. The terms “nose,” “hollow,” and “side slope” follow the usage by J. T. Hack and I. C. Goodlett, “Geomorphology and Forest Ecology of a Mountain Region in the Central Appalachians,” Professional Paper 347, United States Geological Survey, 1960, 66 pp. The terms denote, respectively, areas of convex, concave, and straight contour patterns as viewed from upslope.
22. The total rainfall recorded at Castle Grant Plantation in 1973 was 1000 mm, which is less than two-thirds of the mean annual rainfall for that area (1725 mm), on the basis of data presented by C. C. Skeete, “Barbados Rainfall,” Department of Science and Agriculture, Barbados, Pamphlet No. 9 (1931), pp. 5-18.
23. The term “free degradation” was introduced by J. N. Hutchinson, “The Free Degradation of London Clay Cliffs,” Proceedings, Geotechnical Conference, Oslo (1967), Vol. 1, pp. 113-18 to denote the course of hillslope denudation by mass-movement on slopes which were no longer subject to undercutting at the slope base.
24. P. Martin-Kaye and J. Badcock, “Geological Background to Soil Conservation and Land Rehabilitation Measures in Barbados, West Indies,” Report of the Third Caribbean Geological Conference, 1962, pp. 131-4.
25. Report of the Technical Assistance Mission of the Office of Regional Development of the Organization of American States to the Ministry of Agriculture of Barbados, “Scotland District of Barbados: Evaluation of the Problems and Treatment of Erosion and Unstable Ground,” General Secretariat, O. A. S. Washington, D.C. 1971, 84 pp.
26. Tarn, op. cit. footnote 5.
27. For a discussion of the mechanisms involved in progressive failure see L. Bjerrum, “Progressive Failure in Slopes of Over-Consolidated Plastic Clay and Shales,” Journal of Soil Mechanics and Foundations Division, Transactions, American Society of Civil Engineers, Vol. 93 (1967), pp. 1-49
28. J. T. Christian and R. V. Whitman, “A One-Dimensional Model for Progressive Failure,” Proceedings, Seventh International Conference on Soil Mechanics and Foundation Engineering (Vol. 2) 1969, pp. 541-43.
29. Tam, op. cit. footnote 5.