Fault Zone Rocks at Clarke Head Part 2

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More pictures of rock textures and patterns seen on the shore at Clarke head, near Parrsboro, Nova Scotia. At this site the fault zone sedimentary rocks include Blomidon Formation Triassic red sandstone and siltstone with strata laid down in repeating cycles, and preserved water ripple marks much in evidence. Igneous North Mountain Formation basalt from Jurassic period rift volcanism is present high in the cliff and not shown here for lack of accessibility. Light grey sedimentary Windsor Group Carboniferous limestone strata is also present. Large blocks of Precambrian metamorphic rock have been brought up from deep down by the faulting. These blocks, sometimes huge, are found in the breccia and include garnet-grade schist. Gypsum is common in the breccia, as boulders and as matrix. The boulders from the mega-breccia weather out from the cliff deposits and lie together with numerous smaller boulders, shards, and fragments littering the beach, varying in colour and composition as you walk along the waterline.

REFERENCES

Nova Scotia Field Guide, Arthur D. Storke Memorial Expedition, Department of Earth and Environmental Sciences, Columbia University in the State of New York, August 23 to September 2, 2012.

7 Replies to “Fault Zone Rocks at Clarke Head Part 2”

  1. You certainly know how to bring out the best in rocks. This is a lovely collection of photographs. Can you explain how ripples are preserved in rock? We see this phenomenon in limestone in northern Ohio, too.

  2. Thank you, Linda. Ripples in rock are quite common because so many sedimentary rocks were formed in aquatic environments such as river beds and shoreline coastal situations. The current or wave ripples can be preserved if the surface contours and patterns of these relatively coarser and heavier particles are rapidly buried in a thick deposit of finer mud particles. This could result from a flood event, for example. There are a couple of posts in my blog about rock ripples:
    https://natureinfocus.wordpress.com/2014/04/28/sand-ripples-in-rocks-at-cape-enrage/
    https://natureinfocus.wordpress.com/2016/06/22/rippled-rock-at-point-pleasant-park/
    https://natureinfocus.wordpress.com/2014/04/26/from-ripples-to-rock-patterns/
    A very useful book is Sedimentology and Stratigraphy by Gary Nichols, 2nd Edition 2009, published by John Wiley and Sons, ISBN 978-1-4051-3592-4 (Chapter 4 Processes of Transport and Sedimentary Structures pp 44-68).

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