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Title: Relative-age dating of Neoglacial moraines, Jotunheimen, southern Norway : the potential of the Schmidt hammer
Author: McCarroll, D.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1987
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This thesis represents a critical assessment of the potential of the Schmidt hammer in dating boulder surfaces. Although primarily concerned with the potential of the Schmidt hammer for differentiating moraines which may pre-date the 'Little Ice Age' maximum (c. 1750 AD) in Jotunheimen, southern Norway, many of the results are of wider relevance. Over 30,000 Schmidt hammer rebound values were collected from 138 sites on 7 glacier forelands. Four factors are found to influence Schmidt hammer results: instrument errors, variations in lithology, degree of boulder surface weathering and degree of boulder surface roughness. The influence of each is examined and its potential as a source of error in the interpretation of Schmidt hammer results assessed. Particular attention is paid to boulder surface roughness, which may reflect transport history or the differential weathering of surface minerals. An instrument was designed and constructed allowing quantification of roughness parameters in the field. Variation in R-values parallels variations in boulder roughness due to differing transport histories. Boulder roundness provides a surrogate measure of boulder surface roughness and facilitates the isolation of sites with anomalously low R-values. Most low R-values obtained from moraine ridges are explained by variations in lithology and by the pushing and re-working of older, weathered material. No moraines could be unequivocally dated to before the 'Little Ice Age', although in some cases the Schmidt hammer results do not preclude such a possibility. It is concluded that Schmidt hammer rebound values do not provide a simple index of surface age. They should be interpreted with caution, and the influence of extraneous factors assessed critically before conclusions are drawn.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available