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MethodsA measured section of the beds comprising the folds of the study area, a survey of control points, and three areas of detailed mapping form the basis for the description and analysis in this study. For ease of reference, the beds are divided into six sections, north to south (younging direction), according to fold form and exposure (Figure 8).
The thickness of beds exposed in the study area was measured or estimated as appropriate for the various levels of exposure:
| Sandstone and shale layers of accessible beds greater than 10 cm thickness were measured individually. |
| Intervals of thinner intervening beds were measured as a whole, denoting the number of beds, and estimating the sandstone to shale ratio. |
| Thickness of inaccessible and variably covered sections was estimated using road distance and general strike and dip of adjacent beds. |
Beds were traced through folded sections if feasible. Where beds disappeared beyond visible access, they were traced one limb to another by reference to distinctive packages of beds. Distinction was based on a combination of factors including patterns of bed thickness, layering or separation tendencies in some beds, calcareous layers and boudins, and relative resistance of beds.
Figure 8. N-S cross-section of folds with axial survey points, and map view of axial survey points. Hinges number 1 to 18 in Sections I to IV and 21 to 23 in Section VI. Appendix C has a set of photographs of the outcrop.
Beds, joints, and faults in the folds of Sections I, III, and VI (Figure 8) were mapped in more detail in the field, at a scale of approximately 1:25 onto 11"x18" photographs. Photography was done with a 50 mm lens mounted on a 35 mm SLR camera. Prior to photography, three nonlinear control points per photo area were flagged on the outcrop along with hinges of folds and camera locations. The flagged points, hinges, and camera locations were then surveyed with a total station. Coordinates of surveyed points were used to determine distances between points and as a basis for removing photographic distortion.
