Editing Middle and Upper Carboniferous rocks (Millstone Grit and Coal Measures) of the Sheffield region - an excursion

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The quarry is located to the right of the road at the top of a grassy bank, just after crossing over the roundabout with the junction of the A629. The quarry face may be in variable states of degradation but most of the features described below should be exposed. The gentle northeast dip ([[:File:YGS_YORKROCK_FIG_10_03B.jpg|Figure 10.3b]]) is clearly visible, as is the range of rock types that make up typical Coal Measure cycles. Shales and mudstones with ironstone nodules, in which comminuted plant debris is locally abundant, dominate the sequence. Thin coal seams, seatearths and variably developed siltstones and fine-grained sandstones also occur. The mudrocks are dominantly non-marine but show evidence of occasional marine incursions; the siltstones and sandstones are the result of mainly fluvial activity, while the coals and seatearths indicate plant colonization during periods of emergence.
 
The quarry is located to the right of the road at the top of a grassy bank, just after crossing over the roundabout with the junction of the A629. The quarry face may be in variable states of degradation but most of the features described below should be exposed. The gentle northeast dip ([[:File:YGS_YORKROCK_FIG_10_03B.jpg|Figure 10.3b]]) is clearly visible, as is the range of rock types that make up typical Coal Measure cycles. Shales and mudstones with ironstone nodules, in which comminuted plant debris is locally abundant, dominate the sequence. Thin coal seams, seatearths and variably developed siltstones and fine-grained sandstones also occur. The mudrocks are dominantly non-marine but show evidence of occasional marine incursions; the siltstones and sandstones are the result of mainly fluvial activity, while the coals and seatearths indicate plant colonization during periods of emergence.
  
Point '''A''' (not shown on [[:File:YGS_YORKROCK_FIG_10_03A.jpg|Figure 10.3a]], [[:File:YGS_YORKROCK_FIG_10_03B.jpg|Figure 10.3b]]) is the level of the Joan Coal and overlying shales; these are usually obscured by scree. The Joan Coal lies approximately 14 m below the sandstone bed at '''B'''. The dark grey shales immediately above the coal have yielded the inarticulate '''brachiopod''' ''Lingula ''(horizon equivalent to Clay Cross Marine Band in this area). The geological features within the 15 m of strata exposed in the quarry may be followed on the log ([[:File:YGS_YORKROCK_FIG_10_03A.jpg|Figure 10.3a]]) with reference to the five prominent beds or units '''B–F'''. Point '''G''' (not shown on [[:File:YGS_YORKROCK_FIG_10_03A.jpg|Figure 10.3a]], [[:File:YGS_YORKROCK_FIG_10_03B.jpg|Figure 10.3b]]) is the level of the Lidgett Coal (rarely exposed) which occurs approximately 5.5 m above the top of the sandstones at '''F'''. Thin coal seams are present between the sandstones at '''F''' and the Lidgett Coal.
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Point A (not shown on [[:File:YGS_YORKROCK_FIG_10_03A.jpg|Figure 10.3a]], [[:File:YGS_YORKROCK_FIG_10_03B.jpg|Figure 10.3b]]) is the level of the Joan Coal and overlying shales; these are usually obscured by scree. The Joan Coal lies approximately 14 m below the sandstone bed at B. The dark grey shales immediately above the coal have yielded the inarticulate brachiopod ''Lingula ''(horizon equivalent to Clay Cross Marine Band in this area). The geological features within the 15 m of strata exposed in the quarry may be followed on the log ([[:File:YGS_YORKROCK_FIG_10_03A.jpg|Figure 10.3a]]) with reference to the five prominent beds or units B–F. Point G (not shown on [[:File:YGS_YORKROCK_FIG_10_03A.jpg|Figure 10.3a]], [[:File:YGS_YORKROCK_FIG_10_03B.jpg|Figure 10.3b]]) is the level of the Lidgett Coal (rarely exposed) which occurs approximately 5.5 m above the top of the sandstones at F. Thin coal seams are present between the sandstones at F and the Lidgett Coal.
  
 
Please keep any disturbance of the rock face to a minimum.
 
Please keep any disturbance of the rock face to a minimum.

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