Applied palaeontology in the Chalk Group: quality control for geological mapping and modelling and revealing new understanding

Woods, Mark

doi:10.1016/j.pgeola.2015.11.003

Cited by 12 publications

(10 citation statements)

References 28 publications

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“…In the Guildford district, the base of the Newhaven Chalk lies close to the base of a minor escarpment, analogous to that seen in the South Downs (Aldiss et al, 2012), although rather more subdued (Woods, 2015 , fig. 4).…”

mentioning

confidence: 82%

“…Peake's (2002) plea arose in part from his view that there is a risk that this valuable resource, especially the older material (much of it compiled by amateur geologists, as by Peake himself), would be 'consigned to historical junk-bins'. In reality, BGS chalk surveyors make full use of existing biostratigraphical records of any vintage (Woods, 2015;Woods et al, 2002), as well as routinely commissioning new macrofossil and microfossil determinations, such as those cited in this paper (Woods, 1994(Woods, , 1995a(Woods, , 1995b(Woods, , 1997. Although many of the old chalk pits recorded in the 19 th and early 20 th centuries are now degraded or infilled, BGS surveying has yielded a huge amount of new biostratigraphical and lithological data from field brash, animal burrow spoil, and from relatively modern exposures, commonly at far greater densities than found by any of the earlier surveyors.…”

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confidence: 99%

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Comments on “Gale, A S., Norman Berry Peake, 1921-2010, a chalk revolutionary” [Proc. Geol. Assoc. 128 (2017), 829-839], and “Gale, A S & Lovell, B., The Cretaceous-Paleogene unconformity in England: Uplift and erosion related to the Iceland mantle plume” [Proc. Geol. Assoc. (2017) doi.org/10.1016/j.pgeola.2017.04.002]

Aldiss

Farrant

Hopson

2018

Proceedings of the Geologists' Association

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Certain misunderstandings expressed in two recent papers about the status of the ongoing revision of the geological maps of the Chalk in a large area of southern England, and about the methodology being used in that process, are here corrected. The contrast between a 'lithostratigraphical' and a 'biostratigraphical' approach to Chalk mapping is illustrated with an example area in the North Downs of eastern Surrey, western Kent and the adjacent part of Greater London. It is likely that significant faulting is present in the Chalk of this area, including a normal fault with a throw of about 30 m that passes under Croydon. The area provides the best available opportunity to observe in the field, and to map in exposed Chalk, structures that are likely to be similar to those that occur down-dip under London, concealed beneath Palaeogene cover.

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mentioning

confidence: 82%

mentioning

confidence: 99%

Comments on “Gale, A S., Norman Berry Peake, 1921-2010, a chalk revolutionary” [Proc. Geol. Assoc. 128 (2017), 829-839], and “Gale, A S & Lovell, B., The Cretaceous-Paleogene unconformity in England: Uplift and erosion related to the Iceland mantle plume” [Proc. Geol. Assoc. (2017) doi.org/10.1016/j.pgeola.2017.04.002]

Aldiss

Farrant

Hopson

2018

Proceedings of the Geologists' Association

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“…The succession is punctuated by numerous regionally extensive lithostratigraphical horizons including hardgrounds, sponge beds, marl seams, and various types of flint bands (semi-tabular, nodular and sheet-flints). Some are local in extent, sometimes arranged in complex 3D geometries; others are more regional scale or basin-wide features (Woods, 2015;Mortimore, 2019). They have an important role in the development of dissolutionally enlarged conduit systems, forming potential inception horizons along which dissolution is focused (Lowe & Gunn, 1995;Lowe, 2000).…”

Section: Chalk Stratigraphymentioning

confidence: 99%

Stratigraphical influence on chalk cave development in Upper Normandy, France: implications for chalk hydrogeology

Ballesteros¹,

Farrant²,

Nehmé³

et al. 2020

IJS

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Classically, the Upper Cretaceous Chalk Group aquifer of northwest Europe is conceptualized as a homogenous dual-porosity aquifer, with high porosity related to its fine-grained porous matrix, and intermediate hydraulic conductivity associated with fractures. However, an increasing number of hydrological studies visualize the Chalk as a heterogeneous karst aquifer due to the localised presence of dissolutionally enlarged conduits. Field investigation suggests that cave development is guided by distinct stratigraphical and tectonic discontinuities within the rock mass. Identifying which potential inception horizons within the Chalk aquifer are favoured, and why, is important for developing future robust conceptual models of groundwater behaviour. This study focusses on the Chalk of the Upper Normandy region in France where karstic conduits are common and are linked to major sources of groundwater for public water supply. We analyse the geometry and geomorphology of six chalk caves exposed in the Seine Valley with an aggregated length of over 5.7 km, along with other caves in southern England, and identify the key inception horizons associated with their development. The data shows that prominent Turonian, Coniacian and Santonian hardgrounds have influenced the development of 68% of the studied caves length, with sheet-flints and marl seams also playing a prominent role. Caves developed on or between hardgrounds typically display a complex interlinked anastomotic passage network, whereas passages subjected to paragenetic conditions caused by a high sediment flux tend to be concentrated into fewer, larger conduits. The new evidence from Normandy and Southern England demonstrates the role of lithostratigraphy, and in particular stratigraphical discontinuities on conduit development. The data reinforces the idea that the Chalk aquifer should be viewed as a heterogeneous triple porosity karstic aquifer, in which conduit development is influenced by key stratigraphical discontinuities. This improved conceptual model can be used to develop better groundwater flow models and improved catchment delineation.

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“…They tend to be poor competitors for substrate space, with no active defence against overgrowth of the sides of their branches by bryozoans and other encrusters. On the other hand, their small, widely spaced lophophores are Hopson (2005) and stratigraphy for the Southern Province after Woods (2015) advantageous if food supply is low (Okamura et al 2001), while the widely dispersed zooids indicate a fugitive strategy allowing survival of some zooids in the face of localised mortality of zooids (Buss 1979;Jackson 1979).…”

Section: Runnersmentioning

confidence: 99%

Colony growth strategies, dormancy and repair in some Late Cretaceous encrusting bryozoans: insights into the ecology of the Chalk seabed

Taylor

Martino

Martha

2018

Palaeobio Palaeoenv

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Bryozoans are among the most common macrofossils in the Late Cretaceous Chalk. They include many species that encrusted hard substrates, notably echinoid tests, forming habitat islands on the Chalk seabed. The growth strategies adopted by these bryozoans, as well as the occurrence of reparative structures, provides evidence of the conditions experienced by bryozoans and other benthic animals during the accumulation of this unique pelagic sediment deposited over large areas of the continental shelf. Here, we use historical material in the Natural History Museum, London, to provide qualitative evidence that whereas available substrates, including irregular echinoids, were long-lasting, most individual bryozoan colonies were probably short-lived. Some cheilostome species produced heavily calcified polymorphic zooids at the outer edges of the colony that persisted after loss of the feeding autozooids and became the source of regenerative colony growth. Short-term (possibly annual) periodicity is suggested in the benthic environment experienced by encrusting bryozoans, which may have possibly been a result of cyclical variations in dinoflagellate food supply and/or swamping by unpalatable and potentially poisonous coccolithospheres.

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Applied palaeontology in the Chalk Group: quality control for geological mapping and modelling and revealing new understanding

Cited by 12 publications

References 28 publications

Stratigraphical influence on chalk cave development in Upper Normandy, France: implications for chalk hydrogeology

Colony growth strategies, dormancy and repair in some Late Cretaceous encrusting bryozoans: insights into the ecology of the Chalk seabed

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