Brighton to Newhaven Cliffs is a biological and geological Site of Special Scientific Interest and

Geological Conservation Review The Geological Conservation Review (GCR) is produced by the UK's Joint Nature Conservation Committee and is designed to identify those sites of national and international importance needed to show all the key scientific elements of the geological ...

site, which stretches along the coast between Brighton and Newhaven in East Sussex. An area of is the Castle Hill, Newhaven Local Nature Reserve

Geology

Brighton to Newhaven Cliffs provides the best and most extensive exposure of an important chronological fossil site in England. The gentle folding and the ease of access to the cliff exposures make this an important collecting site for faunas of the upper

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya (million years ago) and 83.6 ± 0.7 mya. ...

and lower

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

. It is an increasingly important reference section for the

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', th ...

. Black Rock is a key for the study of Quaternary Stratigraphy and has attracted scientific interest for over 150 years. The modern sea cliff at Black Rock obliquely intersects a fossil cliff and abrasion platform cut in the Upper Chalk. The platform is overlain by raised beach deposits of sand and shingle which contain shell fragments which amongst other methods have given the beach and cliff a general date from the second half of the last ( Ipswichian) interglacial. The angle between the beach and the old cliff is filled by great quantities of coarse

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...

rubble apparently derived from the

weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement) ...

and

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

of the cliff in Devensian times. Chalk muds and fine chalk gravel and grit, are banked against the rubble on the west and may represent fan deposits. The muds contain appreciable quantities of loess and are overlain by further, coarser

solifluction Solifluction is a collective name for gradual processes in which a mass moves down a slope ("mass wasting") related to freeze-thaw activity. This is the standard modern meaning of solifluction, which differs from the original meaning given to it ...

deposits. The chalk rubble and solifluction deposits are particularly notable for their fossil remains of many Devensian mammals, including Elephas primigenius, Tichorhinus antiquitatus and

Equus caballus The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...

. The landforms, stratigraphy and mammal remains at Black Rock provide an extremely valuable record of former

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardise ...

s and changing environmental conditions during the last few

glaciations A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betwe ...

which have affected this area, Southern England, unlike much of the rest of the UK has not been affected by full scale glaciation. An area of the cliff at

Saltdean Saltdean is a coastal village in the city of Brighton and Hove, with part (known as East Saltdean) outside the city boundary in Lewes district. Saltdean is approximately east of central Brighton, west of Newhaven, and south of Lewes. It is ...

provides probably the finest example of conjugate

normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tecton ...

s in the Chalk of southern England. This exposure of Upper Chalk lies on the southern flank of the Weald anticline, an upward flexure of the crust and the major geological structure of south-eastern England. The faults run in a north-northeasterly direction, at right angles to the trend of the anticline. These structures were probably formed by stretching of the crust parallel to the axis of the anticline during an episode of crustal compression in the mid

Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago. The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...

. The formation of the Wealden Anticline is related to the formation of the Alpine Chain to the South. Along much of the cliffed coast between Brighton and Newhaven (and beyond to Eastbourne), frost involution structures can be seen in the upper meter of the chalk cliff. These involutions appear as repeated 'U' (festoon) shaped structures and date from the Devensisn (last glacial period). Frost heaving broke up the sub-surface sedimentary layers of chalk turning small slabs into a more and more upright orientation towards the surface, to be covered by present day soil. The centre of the 'U' structure is a fill of finer chalk and sands giving a more orange / yellow appearance. These structures have a polygonal surface manifestation which can be revealed by stripping away turf and soil. Slope angle appears to have had an effect on their formation. Where the gradient exceeds 20 degrees solifluction appears to have been a more dominant process preventing their formation. This may link to the patterned ground features of stone nets becoming elongated by gradient resulting in stone stripes as seen in modern periglacial environment and in relic locations such as Dartmoor.

Undercliff Walk

The Undercliff Walk is a path at the foot of the cliffs from Black Rock, Brighton to

. When it is open, this seafront route is popular with walkers and cyclists. However, Brighton & Hove City Council has often had to close it after rockfalls such as during the winters of 2000/01, 2012/13, 2020/21 and 2022/23. Netting and other devices have been placed on parts of the cliffs known to be unstable to prevent rocks from falling on to the path.

References

External links

* {{SSSIs East Sussex Sites of Special Scientific Interest in East Sussex Geological Conservation Review sites Newhaven, East Sussex Brighton Cliffs of England