Belton's Jurassic park

Take a geological hike from Belton House to Bellmount Tower and time travel forward 30 million years! Below your feet is the real Jurassic Park.

The Lincoln Edge resembles a multi-layered sandwich, tilting down towards the east and exposing the west-facing rock layer filling. The oldest rock is at the bottom, the youngest at the top. Belton sits at the foot of this escarpment, with Belmount Tower on the top.

Vertebrate fauna of the Charmouth Mudstone Formation

Belton House is built on sand

Mixed with 5% gravel, the River Witham has deposited this from 3 million years ago (mya) to now. Perhaps 5 to 10 m thick, based on boreholes upstream in Grantham, it covers Charmouth mudstone. This was laid down 183 to 199 mya during the early part of the Jurassic period by shallow seas.

That mudstone runs all the way from Lyme Regis, Dorset to Market Weighton in Yorkshire. If we could only excavate it, we too like Mary Anning would find ammonites, marine reptiles and plant-eating dinosaurs.

Walk up Bellmount Avenue towards the Tower, level with Old Wood, to step on 'head'.

Head

Is rock debris and/or clay washing down from a hill. Deposited by the slow viscous downslope flow of waterlogged soil. It arises during the thawing of seasonally frozen ground. The flow was initiated by meltwater from thawing ice. That melting ice relates to an ice age 3 mya. The last ice age was at a peak 20,000 years ago. But then Belton lay free from ice cover in a tundral landscape with lobes of thick ice north, east and west. Head is found underlying the two lakes and stream running into the Mirror Pond and on into the Witham. Beneath all that still lies Charmouth mudstone.

200 million year-old belemnite fossils about 5 to 10 cm long. The trench view in the Deer Sanctuary looks west towards the fence with the public park on the other side. The parish boundary is seen as a bank to the far left.

Fossils

Once in the Deer Sanctuary, Charmouth Mudstone is directly underfoot, but covered by soil. But, at last we get to view some Belton fossils!

During the 2015 archaeological dig belemnites 'swam' into view, now 72 m above sea level. The Belemnite Marl Member of the mudstone is ~20 to 27 metres thick.

Belemnites were carnivorous and free swimming squid-like creatures with a long bullet shaped body. The soft parts are long gone, but the animal’s tail, held its skeleton. It is the part commonly found as a fossil.

Belemnite reconstruction

One found in Germany with the soft body parts fossilized.

Marlstone Rock

Moving east towards and across Five Gates Lane, crops out an iron rich sandstone deposited in a shallow sea approximately 174 to 191 million years ago in the Jurassic. Marlstone contains the ancestors of oysters and mussels. From 1858, there was once flourishing iron-ore industry. In 1915, over 3 million tons of ore were quarried in Lincolnshire, second only to the York area.1 The ore went by rail to Derbyshire for smelting. Ore was again excavated in Lincolnshire to make weapons during WW2.

The marlstone finishes at the 200m contour line just beyond the car park gate to Bellmount Tower. Three kilometres north at Honington, a railway ran into open cast mines on this contour. Fortunately, Bellmount was spared. Boreholes drilled in 1952 on the Syston & Belton estates revealed too little iron for profitable extraction in peacetime.

Whitby mudstone and limestone

Almost to the Tower is Whitby mudstone. Fossils that may lie beneath are carnivorous pterosaurs with a 30 ft wingspan. More flying lizards than birds, fossilized skeletal remains have been found at Winterton, Lincolnshire and in the Cambridgeshire Fens. To right Parapsicephalus one species found in this rock layer.

And just a pterosaur flight of 20 miles from Belton, the 2019 Rutland Water ichthyosaur in Whitby mudstone, left. Thought to be Temnodontosaurus trigonodon, it measures around 10 metres in length. A plesiosaur was discovered at nearby Saltersford, Grantham in 1914. One of these marine reptiles under our Belton Park?

Northampton Sands

Rest under Bellmount Tower built upon 6 m thick Northampton Sands. Formed by a shallow sea, the stratum hides more dinosaur remains. One is a 175 mya sauropod (see left). Hebiverous and the largest of all dinosaurs and the largest land animals that have ever lived. This dinosaur up to 26 m long could reach above the Tower at a height of 22m.

Lower Lincolnshire Limestone

Finish with a walk in Bellmount Woods planted on Lower Lincolnshire Limestone, sedimentary bedrock formed approximately 168 to 170 mya. Exploited since Roman times, it yields the Collyweston stone slate that roofs Burghley House, once marital home to Elizabeth Brownlow, Young Sir John and Alice Brownlow's eldest daughter.

It necessitates a hard frost to split it into slates and so, quarrying took place across six weeks in winter. Nowadays, with global warming the stone is artificially frozen for 3 days as for the re-roofing of Apethorpe Hall. The original process is illustrated below.

The fissile rock, known as log was mined by hand. After undermining the log to a depth of 12 to 15 feet the pillars were knocked out and the log allowed to fall.

Over Winter the log laid in fields, kept wet day and night.

Once the frost had split the fissile layers a cliving hammer separated the slates.

In Belton's vicinity, this rock layer is used for crushed rock aggregate. Review of Old Mineral Permissions (ROMP) that date back to 1943 to 48 allow reactivation of quarries. Plans for a five-million tonne quarry at Denton were narrowly rejected in 2018, but those for nearby Sudbrook Quarry for gravel extraction were permitted.

The Lower Lincolnshire limestone beds a little below the ground surface are seen near Colsterworth in 2022, to be replaced with landfill.

Limestone used for Belton House & Bellmount Tower

Paradoxically, the stone used for Belton's buildings is not present at Belton itself. That stone comes from quarries exposing the Upper Lincolnshire Limestone a maximum of 15 m thick. It lies above the Lower Lincolnshire Limestone. The dividing marker is the 'Crossi' bed which is distinguished by the fossils it contains. The nearest 'Upper' layer is a quarry marked by a clump of trees 400m north east of the north east corner of Bellmount Wood. It is still excavated at Copper Hill quarry, Ancaster and further afield at Heydour and Clipsham. The quoins of the mansion derive from Ketton.

At Ketton, the quarries provide a cross section through the different rock layers, starting with Whitby mudstone. Continuing up through the Lincolnshire limestone, then onwards and upwards to rock types that if ever present at Belton have long eroded away.

Those rock layers are illustrated left.

Oil & Gas

Not to be seen at Belton! Nonetheless, Belton overlies the East Midlands Oil Province. We know from the Visitors Book that the D'Arcy Exploration Co. Ltd (later to become British Petroleum) visited Belton in 1936. That company went on to exploit the Eakring, Nottinghamshire oil field in 1939 and Nocton, Lincolnshire - drilled in 1943. Belton was spared the Plungar oil experience of 1954 seen in this newsreel. It was hoped that Plungar, 11 miles from Belton, would become the Little Persia of Leicestershire.

Why the Lincoln Edge?

Lastly, what is the explanation for the dip to the east, the uplift that reveals our multi-layered Jurassic sandwich? The Lincoln Edge, the limestone escarpment runs over 50 miles from the Humber to the Leicestershire border south of Grantham. Originally the older and deeper carboniferous limestone was folded, buckled upwards by compression from the plate tectonics that drove the continent-continent collision of Euramerica and Gondwana, roughly 280 to 380 mya, the Variscan orogeny (figure above, Swinnerton & Kent 1981).

The subsequent sedimentary layers like those of the Jurassic were overlaid horizontally. But later tensional stress, pulling apart of the carboniferous layer caused tilting. Tectonic action led to the North Sea Basin subsidence that has allowed tilting to the east. Additionally, opening of the Atlantic Ocean and the development of the Iceland were major factors in uplift and exhumation of the British Isles to the west. Rocks that crop out across southern Britain were exhumed from depths of as much as 2.5 km during Cenozoic time, 66 mya.

Discover more geology with the British Geological Survey viewer.

Fearnsides W.G. 1917. THE SHORTAGE OF THE SUPPLY OF NON-PHOSPHORIC IRON ORE. Journal of the Royal Society of Arts Vol. 65, No. 3384, SEPTEMBER 28, 1917.

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