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Stone buildings—pillars, lighthouses, walls, arches, bridges, buttresses, roof vaults, castles, cathedrals and lettering
Published in John A. Hudson†, John W. Cosgrove, Understanding Building Stones and Stone Buildings, 2019
John A. Hudson†, John W. Cosgrove
The attractiveness of castle architecture extended to the bishops’ castles which were actually palaces for which ‘licences to crenulate’ had been obtained. The crenulations are the undulations along the tops of the castle walls caused by the regularly spaced gaps, crenels, for the use of defensive weapons, see Figure 5.76. In other words, the palaces were made to look like castles even though they were most unlikely to be attacked. Note that licences to build castles in earlier times had not been easy to obtain from the Crown because they could become centres for anti-Royalists, but licences to crenulate were given during less dangerous times. For example, in the time of Edward III, 181 licences to crenulate were issued and this number reduced considerably in subsequent times. In geology, the term ‘crenulation’ is used to describe the microscopic folds that form when a planar rock fabric, such as a slaty cleavage, is folded by a later deformation event echoing the appearance of the crenulated battlements.
Provenance and deformation history of the Eastern Thomson Orogen and implications for the Paleozoic evolution of the Tasmanides (Eastern Australia)
Published in Australian Journal of Earth Sciences, 2020
R. Abdullah, U. Shaanan, K. Lynn, G. Rosenbaum
The phyllitic sample shows a more complex deformation history with evidence of at least three phases of fabric development (Figure 9d). The dominant foliation (S3) is a spaced crenulation fabric that affected earlier quartz–mica domains (Figure 9f), which possibly represent an intense crenulation cleavage (hence S2). The external shape of biotite porphyroblasts suggests that biotite is a pseudomorph replacing an earlier mineral, possibly cordierite. Strain caps around the porphyroblasts (∼0.5 mm) suggest that they formed prior to the S3 crenulation (Figure 9e). Chloritisation indicates that the rock was subjected to greenschist facies metamorphism.
Foliation boudinage structures in the Mount Isa Cu system
Published in Australian Journal of Earth Sciences, 2023
B. J. Williams, T. G. Blenkinsop, R. Lilly, M. P. Thompson, P. Ila’ava
D4a (D4 of Davis, 2004 and Wilde, 2011 and previously D3) locally formed north-northwest–south-southeast-striking fold zones with sub-vertical axial planes, rotating to a northwest strike in the north of the mine. Deformation is typically confined to 10–20 m wide fold zones in the Urquhart Shale, which are locally as much as 100 m wide. The Mount Isa Fold found at the north end of the mine is the largest of these F4 fold zones (Davis, 2004). Most folds in the mine belong to this D4a event, which is dated to 1510 ± 13 Ma (Page & Bell, 1986). A S4 fabric sub-parallel to S2 is observed as a slaty cleavage in dolomitic shale and as a crenulation cleavage in black shale lithologies.
Nappe units along the Caledonian margin in central Scandinavia (Grong–Olden to Nasafjället): definition, distinction criteria and tectonic evolution
Published in GFF, 2018
Reinhard O. Greiling, Benno Kathol, Risto A. Kumpulainen
At Jillesnuole, the floor thrust of the Ammarnäs Complex is a several metres thick shear zone. Shear criteria, in particular mica fish, demonstrate a top-to-the-east transport (Fig. 7D). Mica fish long axes may be oriented normal to the transport direction. However, in places, a preferred alignment of mica fish in the transport direction can be observed, which goes along with a (crenulation) lineation parallel with the transport direction (c. 290º plunge). The floor thrust of the Ammarnäs Complex and thrusts between basement and cover rocks, or between different cover units, appear similar to those of the Stalon Nappe (see above).