315 is an important number for Yorkshire cricket aficionados. No doubt many readers will immediately recall that 315 is the highest county cricket partnership at the Circle ground in Hull, by Herbert Sutcliffe and Len Hutton against Leicestershire in 1937, or possibly that 315 was Tim Bresnan’s total wickets for Yorkshire in List A games, or perhaps that 315 was Surreys total in Yorkshire’s first official match in 1863 (Yorkshire’s first wicket taker was Issac Hodgson, no relation).
315 is of particular importance for Baildon Cricket Club, because the rocks immediately beneath both the Jenny Lane and Belmont grounds are 315 million years old. They also coincide with a key geological boundary in the Upper Carboniferous between the older marine-dominated Namurian and younger terrestrial-dominated Westphalian stages of the Carboniferous period.
The Namurian and Westphalian might seem exotically named. Actually, the Namurian is named after a nondescript village in Belgium (that does imply there are descript villages in Belgium), and Westphalian after a region in western Germany. The last stage of the Namurian has the more familiar sounding ‘Yeadonian’, and the global ‘type-section’ used to define the Yeadonian was at the former brickworks.
However, the particular geological configuration at both our grounds might just mean we need to cut our hard working groundsmen a bit of slack...
The Upper Carboniferous, more than any other era, is emblematic of the geology of northern England, and of Yorkshire in particular. It was a time 100 million years before the dinosaurs, when there was only one continent – Pangaea – where huge rivers carried sediment from far away mountains (they were big, just far away), through forests to swampy deltas emptying into a warm tropical seas. Before you start yearning for a Carboniferous Holiday, there was also giant insects.
Fielding in the Carboniferous wouldn’t have been fun with these beasts. In addition, grass didn’t evolve for another 250 million years. Geology fun fact….when Triceratops were alive all Stegosaurus were already fossils. In fact, a Triceratops is closer in time to an iPad than to a Stegosaurus.
The mineral resources present within Upper Carboniferous strata were of paramount importance in the development of the Industrial Revolution in Britain, and controlled the location and growth of northern cities, including Braford and Leeds. Indeed, the village of Baildon had a thriving coal mining industry. Westphalian-aged coal seams on Baildon Hill were exploited to supply the mills of Baildon and nearby Eldwick – you can still see the mine workings on the hillside. The first documented evidence of coal mines dates back to 1387, and the last coal pit on Baildon Hill was closed in 1863.
Circular mine pits located to intersect Westphalian coal seams, scar Baildon Moor. The 13th green and 14th tee of Baildon golf course for reference.
During the Upper Carboniferous, the UK was located on the edge of a continental plate (Laurussia) in an equatorial position, meaning hot and tropical conditions. The Upper Carboniferous marks a change to global climate, with a change to ‘icehouse conditions’ – this means cyclical growth and decay of polar ice sheets, and resultant dramatic sea level fluctuations even in equatorial regions.
Have you noticed the almost staircase topography around West Yorkshire? This reflects these sea level changes. As sea level fell, huge deltas advanced, fed by sediment eroded from granitic mountains to the north (probably what is now Greenland and Norway). Then as the sea level rose, these deltas were drowned. The periods of delta advance are recorded by the big sandstone cliffs around Baildon, and the periods of drowning are associated with more easily eroded mudstones.
Staircase topography around Baildon reflects the advance and retreat of deltas in the Upper Carboniferous, and helps to form the terraces on which we play cricket. Image taken from West Yorkshire Geological Trust report on Baildon Hill by Parissa Ghaznavi and Alison Tymon
The Jenny Lane and Belmont grounds are on the same sandstone staircase step, which records the last delta advance of the Namurian (and Yeadonian). The big sandstone cliffs around the village, and the 2nd hole at Baildon golf club, are called ‘the Rough Rock’, which has been worked for a wide variety of building stone products (and the underlying Rough Rock flags, were used for roofing). The Rough Rock is a geological record of a huge river system that can be compared with the modern Brahmaputra or Amazon Rivers. The strong and robust Rough Rock also provides the flat step for the Wilsden, Harden, and Hepworth & Idle grounds, in stark contrast to the river dirt and glacial muck at the TPE, Shipley Prov, Bradford & Bingley and Saltaire grounds, for example….
Looking east towards Baildon, with the geology draped on the topography. The red is the Rough Rock sandstone
It is what is above the Rough Rock that is important for Baildon cricket club. The overlying thin succession of mudrock is capped by a thin coal seam: the Pot Clay coal – only 20 cm thick. Under this coal is a ‘seatearth’ – an ancient clay-rich soil horizon used for lining furnaces and making bricks.
In the siltstones above the Pot Clay Coal are non-marine bivalves, ostracods, and fish scales, which passes into a claystone that contains open marine fauna. This is the catchily named ‘Gastrioceras subcrenatum’ marine band, which contains fossils bivalves and goniatites, and marks the end of the Namurian (and Yeadonian) and start of the Westphalian.
The Westphalian marks the gradual shallowing of the sea, and terrestrial conditions to become established. Large, complex forests grew on these low-lying deltas and it is this vegetation that became buried and compressed and over time formed coal seams, which can be found at Baildon Hill.
Then, between 30,000 – 13,000 years ago, an ice sheet 250m thick covered the whole of northern England to just south of Bradford. Ice from the Wharfedale glacier spilled across the watershed to join the Airedale glacier carving out the Millstone Grit to form ‘the Guiseley Gap’. When the climate warmed and the glaciers slowly retreated, they deposited the debris carried along in the ice leaving a layer of glacial till, which all takes us back to our groundsmen….
Other than the naturally flat surface, this geological story could impact drainage. The Rough Rock has high permeability, which means fluid can pass through the rock easily, helping to drain the grounds. However, where the Pot Clay coal and the marine band are preserved they will form a tricky impermeable layer that retains water. Indeed, it is rare to find a coal and marine band so close together, and this interval is well known to mountain bikers for its ‘low friction’ properties. If you throw in some patches of nasty glacial tills, it is amazing we have any drainage at our grounds!