City geology: the Worsley Park wall sport, Manchester
Wall video games are a really geological type of mild leisure and training. I definitely have amused myself by figuring out rocks and their options in partitions since my days as an undergraduate and earlier than. I used to be launched to the identify for the wall sport (apparent, I do know) by Eric Robinson (1996, 1997). Eric’s examples impressed me to plot my very own model of a wall sport in far-flung Jamaica. On the time, I used to be a member of the instructing employees in geology on the College of the West Indies in Mona, Kingston. Every semester, we took the primary yr courses for 3 one-day area excursions. As money was getting ever tighter. I come across the money-saving thought of operating one of many first journeys on campus the place there have been varied ‘city geological’ options worthy of notice. Considered one of these was the stone base of a ruined constructing that had survived from Mona’s days as a sugar plantation. The rocks within the base had been a marvellous combination of blocks and rounded boulders, presumably collected from the mattress of the close by Hope River, which drains the mountainous nation to the east of the college. This journey labored effectively and, after just a few years, the late Trevor Jackson and I printed a area information based mostly on my tour (Donovan and Jackson, 2000).
The first criterion for a geologically fascinating and academic wall sport is an efficient number of rocks. The Mona wall sport was most passable on this respect, with a mix of sedimentary and igneous clasts and labored blocks, and even one specimens with a fault operating by it (Donovan and Jackson, 2000, fig. 3D-H). However such numerous compendiums of rock sorts are uncommon as a result of stone partitions have generally been constructed from a neighborhood supply of rock, corresponding to from free boulders in a river or collected when clearing a area (Anon, 2002). These are generally composed of 1 kind, that’s, the rock that happens in native outcrop (Nield, 2014). But I don’t regard this as an issue – moderately than looking for completely different rock sorts, you possibly can nonetheless search for quite a lot of options proven by one or just a few sorts of native rocks. For instance, when on vacation within the White Peak of the Peak District of Derbyshire, I at all times look at the Carboniferous limestones of the dry stone partitions for fossils.
Sedimentary constructions are additionally an curiosity if mine, notably hint fossils in partitions (for instance, Donovan, 2016, fig. 2H), but additionally physically- and chemically-controlled constructions corresponding to cross-bedding and nodules. This brings me to the Marriott Worsley Park Resort and Nation Membership in Manchester. I first stayed on this most snug of motels with my household in 2009 and have been again a number of occasions since. The principle entrance is down a brief slope with a automotive turning circle, flanked on one facet by a barely sinuous stone wall (Fig. 1). When the location was being rebuilt from its earlier (derelict) agricultural origins right into a luxurious lodge (Redman, 1998), I presume that this wall was constructed from blocks and boulders already out there on the location. In flip, these had been more likely to have been obtained domestically when the unique buildings had been constructed. It’s this wall and its wall sport that I need to describe after my most up-to-date go to.
The rocks that outcrop within the space native to Worsley Park are from the Higher Carboniferous (Pennsylvanian) Pennine Coal Measures Group, notably the Pennine Center Coal Measures Formation, and the Triassic New Purple Sandstone of the Sherwood Sandstone Group, primarily the Chester Pebble Beds Formation (Crofts et al., 2012). The rocks within the Worsley Park wall (Fig. 1) are likely derived from these models and are primarily Coal Measures. All rocks are siliciclastics, primarily medium- to coarse-grained sandstones, with some pebble conglomerates (Figs. 2 and three). The principal mineralogy of the blocks is, the place the floor is clear sufficient to see quartzitic (for instance, Figs. 2B and 3E). The colors vary from pale gray (maybe ganisters; Tucker, 2011, p. 42) to a straw-brown (Coal Measures) to, much less widespread, a deep purple-red (New Purple Sandstone). It’s potential that at the very least among the latter might embrace Carboniferous rocks which were secondarily reddened (Crofts et al., 2012, pl. three). Though boulders are cemented into the wall with bedding horizontal (corresponding to in Figs. 2D, F, H and I, and three) to tilted (Fig. 2B and G) to vertical (Fig. 2 A, C and E), I didn’t see any undoubted cross bedding. In some blocks, the course of bedding is enhanced by the expansion of moss (Fig. 2E). One boulder has a diagenetic improvement of a haematitic iron pan between bedding planes (for instance, Fig. 2A and C).
Pebbles in conglomerates are both preserved in situ, primarily quartz with some rock fragments (Figs. 2E and 3F), or are mud ‘rip-up’ clasts which were partially or completely eroded away, leaving elongate holes within the rock (Figs. 2D, E and G, and 3G). Quartz and lithic pebbles are reasonably rounded (Fig. 3F), suggesting that they’ve a historical past of fluvial transport. Sand grains are usually not well-rounded, however angular, indicating that they weren’t fashioned within the desert (Figs. 2B and 3E).
One factor of which I’m assured is that, though I’ve noticed some fascinating options on this wall, I’ve not caught all of them. Particularly, I failed to search out any proof of fossil crops in rocks that I’ve assumed had been primarily derived from the Coal Measures. I invite these within the Manchester space to see each what I’ve described and to find what I’ve not. I shall be again so as to add to my observations within the not too distant future, I hope. No matter, this is likely one of the uncommon geological websites the place I will be assured that there’s a snug bar and restaurant shut at hand by which to chill out and replicate on my observations.
References
Anon. 2002. Dry Stone Partitions: The Nationwide Assortment. Dry Stone Walling Affiliation of Nice Britain, Sutton Coldfield, 64 pp.
Crofts, R.G., Hough, E., Humpage, A.J. & Reeves, H.J. 2012. Geology of the Manchester district – a short rationalization of the geological map. Sheet Rationalization of the British Geological Survey, 1:50 000 Sheet 85 Manchester (England and Wales): 45 pp.
Donovan, S.Ok. 2016. Annual assembly of the Geological Society of America, Baltimore, November 2015. Deposits, 46: 9-12.
Donovan, S.Ok. & Jackson, T.A. 2000. Subject information to the geology of the College of the West Indies campus, Mona. Caribbean Journal of Earth Science, 34 (for 1999): 17-24.
Nield, T. 2014. Underlands: A Journey by Britain’s Misplaced Panorama. Granta, London, xvii+251 pp.
Redman, N. 1998. A Historical past of the Marriott Worsley Park. Whitbread plc, 26 pp. [Obtainable on-line at http://www.worsleycivictrust.org.]
Robinson, E. 1996. A model of ‘The Wall Recreation’ in Battersea Park. In Bennett, M.R., Doyle, P., Larwood, J.G. & Prosser, C.D. (eds), Geology in your Doorstep: The position of city geology in earth heritage conservation: 163-170. Geological Society, London.
Robinson, E. 1997. The stones of the Mile Finish Street: a geology of Middlemiss nation. Proceedings of the Geologists’ Affiliation, 108: 171-176.
Tucker, M.E. 2011. Sedimentary Rocks within the Subject: A Sensible Information. Fourth version.
Wiley-Blackwell, Chichester, xi+276 pp.
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