Seaford is a small coastal town in East Sussex and home to 22,000
people. Immediately southeast of the town is the Seaford Head Nature
Reserve, an area of stunning scenery and wildlife, and fringed along
its seaward edge by vertical
chalk cliffs. This coastal area is perhaps best known for the famous
Seven Sisters cliffs that continue along the coast towards
Beachy Head in the southeast. The cliff sequence at Seaford Head and
Seven Sisters is separated by the River
Cuckmere, which follows the Cuckmere Valley from its inland source. From the
river mouth the
chalk cliffs continue northwest for 2 miles beneath Seaford.
chalk cliffs and
foreshore at Seaford Head reveal a complex marine
environment dating from the
Cretaceous epoch, 89-86 million years ago. Fossils occur commonly
chalk, in particular
sponges, bivalves, and other benthic fauna that inhabited the
at the time.
Left: Plenty of free
parking is available at the hill-top.
Right: Access to the beach is made via stunning views of
Access to cliffs and foreshore is made via the nature reserve, at the
top of which free
parking is available throughout the year. From
the car park the path splits in three directions (shown above-right), the middle, unsurfaced
route leads to a cattle grid, at which point a second path on the right
leads directly to Hope Gap.
Left: Looking west at
Seaford Head towards the beach access point at Hope Gap.
Right: Three flights of steps lead visitors to and from the
At Hope Gap three flights of concrete steps extend to the beach (shown
above). Fossil can be found in either direction, however for the
purposes of this report the focus is predominantly towards the northwest
(right when looking out to sea).
The geology of Seaford Head
Left: The chalk hill
comes to an abrupt end at Seaford Head, alongside Hope Gap.
Right: The distinctive Hope Gap Sheet Flint within the
The chalk at Seaford Head belongs to the Upper Chalk, and
was deposited during the Coniacian stage of the
Cretaceous epoch between 89-86 million years ago (mya). At this time
Seaford Head and much of Great Britain, along with Europe, lay beneath a
relatively shallow sea around 40°N of the equator, on an equivalent latitude to the
Mediterranean Sea today.
In comparison with present-day conditions, global sea-levels during
the Late Cretaceous were over 200 meters higher. The higher sea levels
likely reflect a combination of extreme greenhouse conditions and
heightened plate tectonics. Elevated plate tectonic activity and the
associated volcanics delivered greenhouse gases to the atmosphere,
fuelling the greenhouse effect. Global high temperatures melted much
(perhaps all) of the ice at high latitudes, introducing significant
amounts of water to the world's oceans. Uplift of the ocean-floor in
regions of active plate tectonics displaced further water onto the
The evidence of higher sea levels is reflected in the white chalk
at Seaford Head. The purity of the chalk indicates its formation
took place far from land, mostly free of terrestrial sands and silts that
would otherwise have coloured it. At Seaford the lower half of the
cliff and foreshore contains a slightly greater volume of
land-sourced sediment, this is particularly evident in the
hardgrounds described below. Chalk is
largely comprised of the the skeletal remains of planktonic algae
known as coccolithophores which accumulated to form a white ooze on the
seafloor. This soft sediment was later compacted and hardened
(lithified) to form chalk - a relatively soft rock itself. To
discover more about chalk
Today the chalk appears above sea level, the
result of lower present-day sea levels and widespread uplifting caused by the pressure of the European
and African continental plates colliding (generating the Alps), a process that took place at
its greatest extent 30-25 mya. More recently, following the end of the
last ice age and subsequent increase in sea levels (albeit to a less
extent than 84 million years ago), the coastline has moved inland,
exposing the elevated chalk to intensive erosion and sculpting it into a
The earliest chalk at Seaford Head belongs to the Lewes Nodular Chalk
Formation and dates from 89 mya. The formation is well exposed on the
foreshore and in the lower half of the cliff (see fig. 1 below). Within the
cliff-face several distinctive marker horizons can be seen, in
particular the Hope Gap Sheet Flint which lies immediately above the
Hope Gap Hardground (described below). A second prominent flint horizon,
known as the Seven Sisters Flint Band (Seaford Chalk Formation), appears
higher in the cliff, further along the coast.
Figure 1: Summary of the
geology at Seaford Head.
From the steps at Hope Gap and onwards towards Seaford an
intermittent ledge protrudes from the cliff base. The upper surface of
indicates the top of the Hope Gap Hardground - a conspicuous layer
comprised of iron-stained nodular white chalk interspersed with
soft, grey chalk (shown below).
Left: The Lewes Nodular
Chalk with the Hope Gap Hardground forming a prominent ledge.
Right: The Hope Gap Hardground with echinoid tests in cross-section.
Hardgrounds are understood to reflect disruptions to the steady
accumulation of chalk forming sediment, during which sedimentation
simply ceased and/or the unconsolidated, soft surface sediments were
stripped away by bottom currents or slumping, exposing the older
chalk sediment. Research has shown that a single hardground may have been
exhumed 16 or more times before long-term burial took place.
The hardground fabric was formed by soft (grey) chalk infilling the
burrows and borings of crustaceans within the hardened (white)
chalk. During this time the irregular surface of the hardened chalk
was encrusted by oysters. Close inspection of the hardground reveals crustacean burrows/borings
cutting through the oyster shells.
Immediately above the Hope Gap Hardground (and Sheet Flint) are the
Beeding Hardgrounds, also belonging to the Lewes Nodular Chalk
Formation. This particular horizon contains a fascinating abundance
of shattered flints still in situ (see below).
Shattered flints in situ within the Beeding Hardgrounds (Lewes Nodular
The shattered flints provide evidence of a significant geological event
that took place after the flint nodules were formed. They are thought to
have formed during mass movements of the chalk sediment, at a stage
where the flint was hard and brittle, but the chalk was not yet fully
no consensus as to what caused the sediment to slide, but the theories
can be narrowed to three possible scenarios: (1) Localised tectonic
uplifting of the seafloor and/or (2) tectonically generated
vibrations (earthquakes). (3) A rapid rise in sea level caused a
sudden increase in overburden, altering the sediment's pore pressure
and reducing its shear strength, and if already on a gentle slope,
inducing sliding. Regardless of their cause, these fascinating
features add a dynamic chapter in the Chalk story.
Moving further along the coast the first of many
deep grooves can be seen penetrating the Seaford Chalk at the cliff-top (shown
These pipe structures, known as dissolution pipes, appear in cross-section as
the cliff retreats. Each vertical pipe was
formed (and continues to do so) as rain water percolates through the
Quaternary sediments, becoming increasingly acidic in the process, and dissolving
the underlying chalk as gravity channels the water along natural
Left: Dissolution pipes in
vertical cross-section at the cliff-top.
Right: A fallen boulder exhibits a dissolution pipe in
horizontal cross-section through its centre.
sediments were transported to the area during the most recent ice age,
115,000 - 10,000 years ago (Devensian stage of the Pleistocene
epoch), during which time much of Britain lay beneath a thick
ice-sheet. Although the limit of the ice-sheet extended only as far
south as Norfolk and the southern parts of Wales, the relative lack
of precipitation across the southern area created a mostly
inhospitable, wind swept, frozen desert landscape. The freezing
winds cut across the exposed land, carrying with them weathered
sands and soils. These sediments, known as loess, accumulated in the
chalk valleys of the Seaford area (which had been shaped by earlier ice ages, as melt water eroded the landscape).
Although the Seaford area was beyond the reach of the erosive
northern ice-sheet, the freezing conditions created localised frost-shattering which loosened and crumbled the sides of the chalk
valleys. These loose rock fragments
accumulated at the foot of the valley sides and would later be
transported along the valleys by rivers and streams to form coombe
Towards the latter part of the Devensian ice age, around 25,000
years ago, precipitation increased and the Seaford area was covered
by snow and ice. This period of relatively high precipitation came
to a gradual end around 14,500 years ago, and was replaced by more
temperate conditions. As temperatures increased seasonal melt waters
flowed along the valleys, carrying with them large volumes of loess
and rock fragments (coombe deposits) into the low-lying
From the steps at Hope Gap the loess and coombe deposits can be
clearly seen in the cliff-face, where they appear as an orange
stained accumulation approximately 10m thick (see below). The photos
show the underlying white contour of the former chalk valley
which itself was probably shaped by the course of the River
Cuckmere at the time.
Left: View east from Hope Gap with the loess and coombe deposits filling the former chalk valley base.
Right: A close-up shows the contour of the chalk valley.
Since the return to more temperate conditions and subsequent
reduction of ice at higher latitudes, global sea-levels have risen
120m. The advancing sea, known as a marine transgression, has
submerged much of the former landmass, shifting the coastline inland and shaping Seaford Head as we know it.
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Where to look for fossils?
Fossils can be found in either direction of the steps at Hope
Gap, although the best exposures are located towards Seaford in the
northwest. The most productive (and safest) place to search for
fossils is on the foreshore at low-tide. Chalk boulders and flint
nodules are scattered along the entire section, providing a constant
supply of fossils.
Left: Lucinda holds a
internal mould of an irregular Micraster echinoid.
Right: Searching for fossils among the loose pebbles on the
Fossils can also be found protruding above the surface of fallen
boulders and in the lower cliff, although the latter is within the
zone of falling rocks, so care should be taken and a hard hat worn.
Left: A bryozoan is
left exposed on the surface of the eroded chalk.
Right: Fossils can be found on the surface of chalk
boulders and in the lower cliff.
Please note the beach platform and cliffs are assigned
SSSI status, which requires visitors avoid damaging (including
hammering) the area. From a fossil collecting perspective this means
it's not permitted to extract specimens that are in situ. Collecting
efforts should be directed towards the loose boulders and pebbles on
As with all coastal locations, a fossil hunting trip is best timed to coincide
with a falling or low-tide. For a relatively low one-off cost we
recommend the use of Neptune Tides software, which provides
future tidal information around the UK. To download a free trial
Alternatively a free short range forecast covering the next 7 days
is available on the BBC website
What fossils might you find?
Below are a selection of finds made at Seaford Head. Where possible the specimen's genus has been indicated below
each photo, if a confident ID can't be achieved a question mark has
been added to indicate so. Among the common finds include echinoids,
brachiopods, bivalves and sponges; less common finds include
crustacean burrows lined with fish scales and starfish remains
Left: A flint nodule containing a fossilised sponge.
Right: A close-up reveals the flint occupies the area running through the hollow centre
(in life) of the sponge.
Left: The mould of
a sponge retained on the surface of a flint pebble.
Right: A cross-section through a sponge.
Left: A regular Temnocidaris echinoid exposed
in situ on the surface of the chalk.
Right: An isolated Tylocidaris echinoid spine.
Echinocorys echinoid filled and surrounded by flint within the chalk on the foreshore.
Right: A partial Micraster echinoid in situ on the foreshore.
Left: A wave shattered
found loose on the foreshore, containing a sediment filled Echinocorys echinoid in cross-section.
Right: A close-up.
Left: A partially exposed Echinocorys echinoid in a loose flint nodule. Right: A split flint nodule containing a
nearly complete Echinocorys echinoid.
segments of a Crateraster starfish found in situ at the cliff base.
Right: A small brachiopod on the air-weathered surface of the
Left: A large flint
'boulder' containing fragments of inoceramid bivalve shell(s).
Right: A close-up.
Left: A fragment of
inoceramid bivalve shell.
Right: A complete Spondylus bivalve visible on both sides of a
although not shown in the photo.
As well as fossils, minerals can also be found, in particular beautiful
quartz crystals within broken flints, and intricate star shape, silver structures within split iron pyrite nodules (shown below).
Left: Quartz crystals
within a broken flint nodule.
Right: The star shaped structure of a split iron pyrite nodule.
Tools & equipment
Left: A strong
rucksack is useful for transporting fossils and tools. Right:
A hammer and chisel are recommended for extracting fossils from the
It's a good idea to spend some time considering the tools and
equipment you're likely to require while fossil hunting at
Seaford Head. Preparation in advance will help ensure your visit is
productive and safe. Below are some of the items you should consider
carrying with you. You can purchase a selection of geological tools
and equipment online from
A strong hammer will be required to split prospective rocks. The
hammer should be as heavy as can be easily managed without causing
strain to the user. For individuals with less physical strength and
children (in particular) we recommend a head weight no more than
Chisel: A chisel is required in conjunction with a
hammer for removing fossils from the chalk. In most instances a
large chisel should be used for completing the bulk of the work,
while a smaller, more precise chisel should be used for finer work.
A chisel founded from cold steel is recommended as this metal is
especially engineered for hard materials.
Safety glasses: While
hammering rocks there's a risk of injury from rock splinters
unless the necessary eye protection is worn. Safety glasses ensure any splinters are deflected away from the eyes. Eye
protection should also be worn by spectators as splinters can
travel several metres from their origin.
Strong bag: When considering the type of bag to use it's worth setting aside
one that will only be used for fossil hunting, rocks are usually
dusty or muddy and will
make a mess of anything they come in contact with. The bag will also
need to carry a range of accessories which need to
be easily accessible. Among the features recommended include: brightly coloured,
a strong holder construction, back
support, strong straps, plenty of easily accessible pockets and a rain cover.
Walking boots: A good pair of walking boots will
protect you from ankle sprains, provide more grip on
slippery surfaces and keep you dry in wet conditions. During your
fossil hunt you're likely to encounter a variety of terrains so
footwear needs to be designed for a range of conditions.
For more information and examples of tools and equipment
recommended for fossil hunting
or shop online at
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Protecting your finds
It's important to spend some time considering the best way to
protect your finds onsite, in transit, on display and in storage.
Prior to your visit, consider the equipment and accessories you're
likely to need, as these will differ depending on the type of rock,
terrain and prevailing weather conditions.
wrapped in foam, ready for transport. Right:
A small compartment box containing cotton wool is ideal for
separating delicate specimens.
When you discover a fossil, examine the surrounding matrix (rock)
and consider how best to remove the specimen without breaking it;
patience and consideration are key. The aim of extraction is to
remove the specimen with some of the matrix attached, as this will
provide added protection during transit and future handling;
sometimes breaks are unavoidable, but with care you should be able
to extract most specimens intact. In the event of breakage,
carefully gather all the pieces together, as in most cases repairs
can be made at a later time.
For more information about collecting fossils please refer to the
following online guides:
Fossil Hunting and
Conserving Prehistoric Evidence.
Join us on a fossil hunt
Left: A birthday party with
a twist - fossil hunting at
Right: A family hold their prized ammonite at Beachy Head.
Discovering Fossils guided fossil hunts reveal evidence of life that
existed millions of years ago. Whether it's your first time fossil
hunting or you're looking to expand your subject knowledge, our fossil
hunts provide an enjoyable and educational experience for all. To find