Fact-checked by Grok 2 weeks ago

Gault

The Gault Formation, also known as Gault Clay, is a geological formation consisting primarily of stiff, pale to dark grey or blue-grey clay and mudstone, with occasional siltstone layers and phosphatic nodules, deposited in a calm, deep-water marine environment during the Early Cretaceous Albian stage approximately 100 to 112 million years ago.^[1]^[2]^[3] This formation is predominantly found in southern and eastern England and equivalents in northern France, where it underlies the Chalk Group and overlies the Upper Greensand Formation, forming a key part of the Cretaceous stratigraphy in the Anglo-Paris Basin.^[1]^[4] It is divided into Lower and Upper Gault members, with the lower part often sandier and the upper finer-grained, reflecting subtle shifts in depositional conditions.^[2]^[5] The Gault Formation is renowned for its rich fossil content, including ammonites, belemnites, bivalves, gastropods, sharks' teeth, fish remains, crabs, and lobsters, which provide valuable insights into Early Cretaceous marine ecosystems and biostratigraphy.^[6]^[5] Historically, it has been quarried for brickmaking, cement production, and phosphatic nodules used as fertilizer, though its shrink-swell properties make it challenging for modern engineering applications, often requiring stabilization in construction.^[1]^[7] In terms of regional extent, boreholes confirm its presence across southeast England, with variations in thickness from about 30 to 100 meters, influenced by tectonic subsidence and sediment supply.^[4]^[8]^[9]

Geological Overview

Definition and Characteristics

The Gault Formation is a geological formation consisting of stiff blue clay or mudstone deposited in a calm, deep-water marine environment during the Albian stage of the Lower Cretaceous period.^[2] It is characterized by pale to dark grey or blue-grey coloration, with a glauconitic and sometimes sandy base, and is known for its plasticity and susceptibility to shrink-swell behavior due to its high clay content.^[1] The formation's lithology reflects deposition in quiet marine conditions, where fine-grained sediments accumulated below storm wave base, typically at depths of 50 to 100 meters. Compositionally, the Gault Formation is dominated by clay minerals, including kaolinite, illite, and smectite, with subordinate vermiculite, chlorite, and mixed-layer clays, alongside non-clay components such as quartz, feldspar, and mica.^[7] It commonly features disseminated phosphatic nodules, glauconite grains, pyrite, and calcareous concretions, with selenite (gypsum) crystals occurring in the upper parts in some regions.^[2] These elements contribute to its stiff, cohesive nature when weathered, often forming low-lying, poorly drained landscapes.^[7] The type locality for the Gault Formation is the cliff section at Copt Point, Folkestone, Kent, England, where the full sequence is exposed and has been studied since the 19th century.^[2] Stratigraphically, it forms part of the Selborne Group and underlies the Upper Greensand Formation and the Chalk Group, typically resting unconformably on the Lower Greensand Group.^[10]

Age and Stratigraphy

The Gault Formation dates to the Middle and Upper Albian stages of the Lower Cretaceous Period, spanning approximately 112 to 100 million years ago.^[7]^[11] This temporal placement is supported by biostratigraphic correlations using ammonite zones, which delineate the formation's progression from the Hoplites dentatus Zone in the lower part to the Mortoniceras rostratum Zone in the upper part.^[7] Stratigraphically, the Gault Formation occupies a key position within the Selborne Group, overlying the Lower Greensand Group with an often unconformable base marked by a phosphatic pebble bed or gritty mudstone in many exposures.^[2]^[10] It underlies the Upper Greensand Formation via a diachronous transition or passes upward into the Grey Chalk Subgroup of the Chalk Group, sometimes with the intervening Cambridge Greensand Member; in areas where the Upper Greensand is absent, the contact with the overlying chalk is unconformable.^[2] This positioning reflects a depositional sequence in a deepening marine environment during the Albian transgression.^[7] The formation is subdivided into the Lower Gault and Upper Gault members, distinguished primarily by lithological shifts. The Lower Gault consists of silty clays and mudstones, representing more proximal or terrigenous-influenced deposition, while the Upper Gault comprises more calcareous clays and mudstones, indicative of increasing marine influence and carbonate input.^[7] These subdivisions are further detailed into numbered beds (I–XIII) in the type section at Copt Point, Folkestone, based on lithology and fossil content.^[2] Thickness of the Gault Formation varies regionally due to depositional and erosional factors, generally ranging from 30 to 50 meters but reaching up to 110 meters in the Wealden area and thinning to as little as 2 meters in northern East Anglia.^[2]^[7]

Geographic Extent

In England

The Gault Formation outcrops extensively across southern England, forming a distinctive band that stretches from East Anglia southwestward through the Home Counties and Wessex to Devon and Dorset, while encircling the Weald in an arc from northeast Kent to the west.^[2] Key exposures occur along the North Downs and South Downs, within the Weald Basin, on the Isle of Wight, and in Norfolk and East Anglia, where it underlies the Chalk Group and is often revealed in coastal cliffs, quarries, and borehole records.^[12] These outcrops highlight the formation's role in the mid-Cretaceous stratigraphic sequence, overlying the Lower Greensand Group and underlying the Upper Greensand or Chalk.^[9] Thickness variations are pronounced due to depositional facies changes and structural influences, with the formation reaching up to 110 m in the Weald Basin, where it attains maximum development amid deeper marine conditions.^[12] It thins significantly northward and eastward across the London Platform, reducing to approximately 2 m in north Norfolk, reflecting shallower shelf environments and overstep onto older substrates.^[12] At Redcliff Point on the Isle of Wight, the formation measures around 22 m thick, comprising silty clays interbedded with sandier horizons.^[13] Local lithological features vary regionally; in East Anglia, the base of the Gault Formation rests unconformably on the Carstone Member of the Hunstanton Formation, marking a transition from sandy substrates to overlying mudstones.^[2] Further west in Devon and Dorset, the formation develops more silty and sandy character, with interbedded mudstones and fine-grained sandstones reflecting proximal shelf influences and proximity to sediment sources.^[14] The formation was first systematically mapped and described during 19th-century surveys by the Geological Survey of Great Britain, with key contributions including detailed sections at the type locality in Folkestone by Price (1874) and Topley (1875), establishing its extent and divisions across English localities.^[2]

In Europe

The Gault Formation and its equivalents are distributed across northern Europe, extending from the Anglo-Paris Basin into adjacent regions such as the Low Countries and northwestern Germany, where they represent Albian-age marine deposits formed in a shallow epicontinental sea. In France, the formation is termed the Argiles du Gault, particularly prominent in Normandy and the broader Paris Basin, where it comprises fine-grained, often glauconitic clays similar in character to the English Gault. These deposits exhibit lateral continuity with the British occurrences, reflecting a shared depositional environment during the mid-Cretaceous transgression across the region.^[15]^[16] The thickness of the Argiles du Gault in French basins varies significantly, reaching up to 100 meters in subsiding areas of the Paris Basin, though it commonly measures 50 to 80 meters in outcrop sections in Normandy. Eastward, toward the Low Countries, the formation thins progressively due to shallower water depths and proximity to emergent landmasses, with Albian equivalents in Belgium attaining up to 150 meters in the subsiding zones of the Mons Basin. In the Netherlands, Albian strata within the broader Lower Cretaceous sequence, such as those in the Holland Formation, range from 100 to 200 meters thick in the subsurface of the West Netherlands Basin. Further east in Germany, Albian clayey-marly sediments in the Lower Saxony Basin, which encompasses parts of the Westphalian region, accumulate to several hundred meters in thickness, marking the eastern extent of these Boreal-influenced deposits.^[17]^[18]^[19]^[20] Biostratigraphic correlation of these equivalents across northern Europe relies heavily on ammonite zonation, which provides a robust framework for regional synchronization. Standard zones such as the Hoplites spathi, Hoplites dentatus, and Anahoplites intermedius are recognized in both the English Gault and continental counterparts, enabling precise matching of Middle to Upper Albian intervals from the Anglo-Paris Basin to the Lower Saxony Basin. This zonation underscores the uniformity of the ammonite faunas despite lithological variations, facilitating cross-border stratigraphic mapping.^[21]^[22]

Paleontological Significance

Marine Fauna

The Gault Formation preserves a rich and diverse marine fossil assemblage, primarily from the Albian stage of the Lower Cretaceous, reflecting a thriving subtropical shelf environment. Invertebrates dominate the record, with ammonites being particularly abundant and serving as key biostratigraphic markers for precise dating of the formation. Species such as Hoplites spathi, Anahoplites planus, and Euhoplites loricatus characterize the lower Gault, while upper levels feature Mortoniceras inflatum and Stoliczkaia dispar, enabling subdivision into zones like the Middle Albian Hoplites dentatus Zone and its subzones (e.g., lyelli and baylei).^[23]^[24] These cephalopods, often pyritized or preserved in phosphatic nodules, highlight the formation's utility in correlating strata across southern England and the Anglo-Paris Basin.^[12] Belemnites, such as Neohibolites minimus and Neohibolites oxycaudatus, are common and indicate stable marine conditions, frequently occurring alongside bivalves like Inoceramus lissa, Birostrina concentrica, and Inoceramus concentricus.^[23]^[24] Gastropods (Anchura carinata), corals (Discocyathus fittoni), crinoids (Nielsencrinus cretaceus), and crustaceans (Notopocorystes stokesi) further diversify the invertebrate fauna, with shelly beds yielding dense concentrations of these groups in mudstone layers.^[23] Vertebrate remains, though less common, include fish fossils such as shark teeth (Lamna appendiculata) and teleost bones, often fragmented but revealing a predatory marine ecosystem.^[23]^[6] The exceptional preservation of these fossils stems from the formation's depositional setting in oxygen-poor bottom waters, which minimized bioturbation and scavenging, allowing over 100 ammonite species alone—along with hundreds of other marine taxa—to be identified across sites like Folkestone and the Isle of Wight.^[23]^[6] This anoxic influence, combined with slow sedimentation in fine-grained clays, facilitated the accumulation of delicate structures, making the Gault a vital archive for Albian biostratigraphy and paleoecology.^[25]

Terrestrial Finds

The Gault Formation, predominantly known for its rich marine fossil assemblage, yields only sporadic evidence of terrestrial life, primarily through reworked or marginally deposited material that hints at proximal landmasses during the Albian stage of the Early Cretaceous. These rare finds, often preserved in phosphatic nodules or erosion surfaces, include vertebrate remains and plant debris, contrasting sharply with the abundant cephalopods and bivalves characteristic of the formation's deeper-water deposits. Key discovery sites, such as the coastal exposures at Folkestone in Kent, UK, have provided the majority of these specimens, where slumping and wave action expose the clay layers.^[26] Dinosaur remains from the Gault are exceptionally scarce, with material attributable to the nodosaurid Acanthopholis horridus known from Folkestone, including vertebrae and other elements scavenged post-mortem by sharks as evidenced by bite marks on the bones. This armored ornithischian represents one of the few definitive terrestrial vertebrate body fossils from the formation and underscores the rarity of such preservations in a marine-dominated setting. Possible theropod fragments, including isolated teeth and vertebrae, are known indirectly through reworking into the overlying Cambridge Greensand Member, where they derive from upper Albian Gault horizons and suggest the presence of carnivorous dinosaurs in nearby coastal environments. Pterosaur fossils, indicating aerial components of the terrestrial fauna, are similarly infrequent but significant, with the first documented azhdarchoid remains—a fragmentary humerus and an elongate mid-cervical vertebra—recovered from the Gault at Wye, Kent, and referable to Azhdarchoidea indet., potentially aligning with the family Azhdarchidae. These specimens, characterized by a reduced neural spine and confluent neural arch on the vertebra, mark an early occurrence of this pterosaur clade in the formation and complement prior indeterminate records, such as Pterodactylus sp. and Ornithocheirus sp., mostly from Folkestone exposures. Such finds imply that flying reptiles foraged over or near the Gault seaway, bridging marine and terrestrial ecosystems.^[27] Evidence of vegetation and invertebrates comes from plant and palynological remains, including fragments of fossil wood in the basal Folkestone Formation sands at Folkestone Warren, often associated with dinosaur tracks and oyster shells in intertidal deposits. Charcoalified wood and miospores (terrestrial spores and pollen) are present in the Gault mudstones, as revealed by palynological analyses showing diverse sporomorph assemblages that indicate input from adjacent land areas, with common taxa reflecting a humid, vegetated hinterland. Rare insect impressions, preserved in fine clay layers, further suggest episodic terrestrial influence, though these are poorly documented and typically occur in reworked contexts at sites like Folkestone.^[26]^[28]

Practical Applications and Properties

Historical Uses

The Gault Formation's clay, prized for its plasticity when fired, was historically exploited in Kent for brick and tile production. Operations at Dunton Green, where the Lower and Upper Gault divisions were quarried from pits rich in fossils, began in earnest in 1862 under the Brick, Tile & Pottery Works established by William Thompson, producing items until reserves were exhausted in 1956.^[29] In central and eastern Kent, such as near Pluckley and Ashford, Gault Clay supported industrial-scale brickmaking from the mid-19th century, facilitated by railway access and mechanized kilns adopted by firms like the Kent Brick and Tile Company by 1880, driven by demand from London's expanding infrastructure.^[30] Phosphatic nodules within the Gault Formation, concentrated in beds like the Cambridge Greensand at its upper boundary, were extensively mined as a source of fertilizer during the 19th and early 20th centuries. Extraction peaked in the Victorian era, particularly from 1848 to 1919, with major operations in Cambridgeshire and Bedfordshire at sites including Burwell, Leighton Buzzard, and Sandy, yielding up to 258,150 tons annually in 1876 and totaling around 2 million tons overall.^[31] These nodules, processed into "chemical manure" at local mills, supported British agriculture by improving soil fertility, generated significant landowner royalties (up to £200 per acre), and created employment in mining and transport until the rise of synthetic phosphates led to decline by the early 20th century.^[31] Additional historical quarrying targeted the Gault's clay for local construction materials, including in the Vale of Holmesdale where it was mixed with sand for bricks.^[32] Weathering processes in the formation could produce gypsum through pyrite oxidation.^[7] Overall, exploitation of the Gault reached its zenith in the Victorian period amid Britain's industrial boom, but waned post-1900 as alternatives like imported guano and chemical fertilizers supplanted natural phosphates, and brickearth deposits proved more convenient for ceramics.^[31]

Geotechnical Challenges

The Gault Formation, primarily composed of stiff to very stiff overconsolidated clay, exhibits high plasticity with median plasticity indices ranging from 41% to 48% across much of its outcrop, though values can exceed 125% in certain overdeepened sequences due to elevated smectite content. This mineralogy contributes to its sensitivity to moisture changes, resulting in significant volume variations; the clay demonstrates very high expansive potential, with swelling strains often surpassing 100% and swelling pressures reaching 110–620 kPa under confined conditions. Undrained shear strength typically falls in the range of 85–148 kPa based on triaxial testing medians, though effective drained strengths are lower, with cohesion values of 7–80 kPa and friction angles of 10°–40°. These properties render the Gault particularly challenging for geotechnical applications, as water ingress can soften the material, reducing stability, while drying induces contraction and fissuring. Slope instability is a predominant issue in the Gault, driven by its low effective shear strength and fissured structure, leading to failures even on gentle inclines as low as 7°. Translational landslides with rotational elements are common, especially in cuttings and embankments, where the formation shows some of the highest failure rates among UK soils; surveys of transport infrastructure indicate failure incidences of 9.6% in cuttings and 8.2% in embankments constructed in Gault clay. Desiccation cracking further exacerbates these risks, forming a network of fissures in the weathered near-surface zone (typically to 1–1.5 m depth) during seasonal drying, which accelerates water infiltration during wet periods and promotes progressive weakening. The clay's shrink-swell behavior, influenced by its smectite-rich composition, amplifies these effects, contributing to subsidence and heave that compromise linear infrastructure and foundations in affected areas. Notable case studies highlight these challenges in southeastern England's transport network. On the A14 motorway in Cambridgeshire, a deep-seated embankment failure in 2001 mobilized an 8 m high slope over 35 m, attributed to elevated pore water pressures (ru = 0.4) from poor drainage in the high-plasticity Gault fill, with effective strength parameters of c' = 5 kN/m² and φ' = 22°. A shallower failure occurred in 2005 along a 2.1 km stretch, involving 0.4 m deep backscarps linked to seasonal moisture fluctuations and vegetation-induced tension cracks. Similarly, a 2000 landslide at Flint Hall Farm on the M25 near London displaced 90,000 m³ of material in a 25 m high cutting through the North Downs, triggered by exceptional winter rainfall raising groundwater levels and exploiting weaknesses at the Gault-chalk interface. More recently, in December 2023, a major landslide on the Isle of Wight near Bonchurch affected approximately 42 ha of terrain, involving slip surfaces in the Gault Clay beneath infrastructure, driven by heavy rainfall and highlighting persistent risks in coastal settings as of 2024.^[33] These incidents underscore the formation's vulnerability in oversteepened engineered slopes, where progressive retrogression can extend failures upslope over decades. Mitigation strategies for Gault-related instability emphasize controlling moisture and enhancing shear resistance. Effective approaches include deep drainage systems, such as horseshoe-shaped filter drains and ejector wells to lower the water table by up to 6 m, combined with structural reinforcement like bored piles (16 m long, 1.05 m diameter) to anchor sliding masses to stable substrata. In embankment repairs, geogrid installation and lime treatment of the clay fill have improved factors of safety from near 1.0 to 1.38 by reducing plasticity and pore pressures. Vegetation management is also critical to minimize desiccation cracking and root-induced stresses. Recent 21st-century geotechnical assessments, informed by LiDAR mapping and updated BGS hazard datasets, have refined risk evaluation for urban development on the Gault, particularly along motorways like the M25–M26 corridor. These studies confirm elevated landslide densities (5–10 per 100 km²) in areas of relict slips and recommend site-specific investigations incorporating climate-driven moisture variability to guide sustainable infrastructure planning in southeastern England.

References

[1]
Gault Formation - British Geological Survey
The Gault Formation is a sequence of clays, mudstone, and siltstones with phosphatic nodules, formed 100-112 million years ago, and prone to shrink-swell ...
[2]
Gault Formation - BGS Lexicon of Named Rock Units - Result Details
The Gault Formation is pale to dark grey or blue-grey clay or mudstone, with a sandy base, and is of Albian Age.
[3]
[PDF] What is Gault Clay?
Gault Clay is a sedimentary rock made of clay and non-clay minerals, dark blue-grey, fine-grained, and formed from finer sediments.
[4]
The stratigraphy of the Gault Formation (Early Cretaceous, Albian) in ...
The mudstones of the Gault Formation, divided into Lower and Upper Gault Members, have been proved in boreholes to underlie the Chalk throughout south east ...
[5]
Gault Clay Page - Bucks Geology Group
The Gault Clay formed in northern Europe during the Early Cretaceous, is a grey clay, and was worked for phosphatic pebbles.
[6]
Fossils from the Gault Clay
The Gault Clay, deposited 100-112 million years ago, contains diverse fossils including ammonites, snails, clams, shark’s teeth, fish, crabs, lobsters, and ...Missing: geology | Show results with:geology
[7]
[PDF] Engineering geology of B ·tish rocks and soils Gault Clay
This report covers the engineering geology of Gault Clay, including its geological framework, mineralogical considerations, geotechnical properties, and ...
[8]
The Base of the Gault in Sussex - Lyell Collection
The presence of a marked break in deposition and, in some areas, of widespread transgression at the base of the Gault clays is well known, but the details of ...
[9]
Selborne Group - BGS Lexicon of Named Rock Units - Result Details
In the extreme west of the outcrop the overstep places the Gault Formation on Triassic mudstones and sandstones. ... Formation is unconformable on the Mercia ...
[10]
Albian - an overview | ScienceDirect Topics
Using the base-Cenomanian age of 100.5 ± 0.4 Ma implies a base-Albian age of 112.95 Ma (± 0.4). This is supported by a U-Pb age of 113.08 ± 0.14 Ma from zircons ...
[11]
A stratigraphical framework for the Lower Cretaceous of England
Thickness: The formation thickens westward from 30 m at Rye to 70 m at Cuckfield and 78 m at Worth. Distribution: Occurs at outcrop in the Weald and at subcrop ...
[12]
[PDF] UK Stratigraphical Framework Series: Lower Cretaceous (Aptian ...
Upper Greensand Formation is thickest in the Pewsey Basin and thins north eastwards. • The well-known diachroneity of the Gault and Upper Greensand formations ...
[13]
[PDF] The Biostratigraphy of the Albian and Cenomanian succession in ...
It varies considerably in thickness from 2 m at Compton Bay, 22 m at Red Cliff and 4.2 m in Ventnor no. 2 Borehole.<|separator|>
[14]
The stratigraphy of the Cretaceous (Albian Stage) Gault and Upper ...
3.2 Lower Gault Member The Lower Gault is present throughout the region. Sandstones and silty mudstones in north Dorset pass eastwards into silty mudstones ...<|separator|>
[15]
[PDF] Notice - BRGM
Albien moyen : Sables des Drillons et Argiles du Gault (Épaisseur : 50 à 60 m). A la base de l'Albien moyen argileux (Argiles du Gault), s'intercale au Sud de ...
[16]
Environmental and climatic controls of the clay mineralogy of Albian ...
In the Argiles tégulines de Courcelles unit, the CaCO3 proportions are between 10% and 15% except in some marly limestones where the CaCO3 content reaches 40%.
[17]
[PDF] Projet Vallée de la Céramique" inventaire des gisements d'argile du ...
Photo n° 2 : Argiles du Gault (Albien supérieur site n° 71). L'épaisseur totale y est de 50 a 30 m. Entre l'Albien supérieur et les formations de la craie ...
[18]
[PDF] Cretaceous lithostratigraphic units (Belgium) - SciSpace
Thickness: May reach 150 m in subsiding zones of the western Mons Basin (Harchies). Age: The fossil assemblages indicate a Middle Albian to. Early Cenomanian ...
[19]
Giant pockmark formation from Cretaceous hydrocarbon expulsion ...
Jan 1, 2018 · 3) is the thickest of the three members of the Holland Formation. Its thickness in the vicinity of the study area ranges between c. 100 and 200 ...<|control11|><|separator|>
[20]
Inorganic geochemistry of Albian sediments from the Lower Saxony ...
Several hundred meters thick, clayey-marly sediments of Aptian/Albian age are deposited in the Lower Saxony Basin of NW Germany, a 'Boreal' epicontinental shelf ...Missing: Westphalian | Show results with:Westphalian
[21]
[PDF] Correlation of Albian European and Tethyan ammonite zonations ...
ammonite subzonal succession in the European faunal province has been accurately documented in the Gault of SE England, France and northern Germany. This ...
[22]
The Vöhrum section (northwest Germany) and the Aptian/Albian ...
An Aptian/Albian boundary stratotype was formally proposed by Owen (1984a), based on a section exposed at Vöhrum (clay pit no. 3) described previously by Owen ( ...Missing: Westphalian | Show results with:Westphalian
[23]
[PDF] PALAEONTOLOGY OF THE GAULT
The first takes in the ventrally grooved ammonites such as Hoplites, Euhoplites, Anahoplites and Dimorphoplhes, which dominate the Lower Gault, and Epihoplites,.Missing: biostratigraphy | Show results with:biostratigraphy
[24]
[PDF] The holostratigraphy of the Albian Stage (Lower Cretaceous) of the ...
London Platform. At Copt Point, near Folkestone (Figure 18), the formation ... Gault Formation Bed IV and Bed 7. Rarely seen in the Rødby. Formation of ...
[25]
Benthic palaeoecology of the Gault Clay Formation (Mid and basal ...
Jan 4, 2020 · ... fossils. The Gault Clay was probably deposited under moderate energy conditions and slow sedimentation rates below wave-base at mid-to outer ...
[26]
The youngest dinosaur footprints from England and their ...
The youngest dinosaur footprints from England, found in the Folkestone Formation, are from theropod, ornithopod, and possibly ankylosaur dinosaurs, indicating ...
[27]
https://www.sciencedirect.com/science/article/pii/S0016787822000463
[28]
First occurrence of azhdarchoid pterosaurs in the Gault Formation ...
Pterosaurs are a rare component of the Early Cretaceous (Albian) Gault Formation of southern England. The only named taxon reported, ...
[29]
The palynology and geology of the Lower Cretaceous (Aptian ...
The Lower Cretaceous in Bedfordshire is represented by sediments belonging to the Lower Greensand Group and the Gault Clay Formation. Within the Lower ...
[30]
Dunton Green Brick, Tile & Pottery Works and Associated Industries
May 18, 2017 · ... Gault Clay, Lower Greensand, Weald Clay and Wealden Sandstone. Certain of these layers eroded faster than others and over millions of years ...Missing: Wye | Show results with:Wye
[31]
[PDF] The brickmaking indusTry in kenT C.1825-1900
Also shown in Fig. 1 is the band of Gault Clay across the county which has also supported brick production at a few centres with access to railway. The ...Missing: Wye | Show results with:Wye
[32]
[PDF] Coprolite Mining - East Midlands Geological Society
They were exploited commercially in. Victorian times as source of phosphate for what was then called “chemical manure”. Working this resource of fertilizer made ...<|control11|><|separator|>
[33]
St. Martin's Plain to Etchinghill - Geomusings
The Gault is a shallow marine deposit comprising dark grey clay and mudstone, about 113 million years to 101 million years old. Gault clay has been used ...