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Left: A large flint echinoid
Propping up a
large flint nodule on the foreshore at
Flint is comprised of Silicon - the second most common element
on Earth. Flint can be found in a variety of shapes and sizes,
ranging from small pebbles to large stones and even in thick sheets.
Flint not only preserves the fossil evidence of former life, but has
also been used in hunting and construction.
Left: A selection
of ancient arrowheads shaped from flint. Right: An
selection of small echinoids preserved as flint.
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Humans have used flints for a very long time. Prehistoric
tools were crafted/formed from it. These tools were and still are
extremely sharp, in some cases even sharper than a modern surgeons
knife! These valuable properties were utilised in a number of early
disciplines including arrow-heads for hunting, as cutting tools, for
preparing food and clothing, as axe-heads for working wood and, of
Long after it was first used to provide tools, its durable
qualities as a building material were recognised. Flint walls became
a prominent part of the southern England landscape. The Romans also
made use of the hardness and durability of flint in their roads and
buildings, and local tradesmen used flint consistently up until the
early-20th century in much the same way.
How did flint form?
The majority of silica found in flint nodules is biogenic
(produced by living organisms or biological processes). Although
today's flint nodules are inorganic, the silica that formed them was
originally sourced from the remains of sea sponges and siliceous
planktonic micro-organisms (diatoms, radiolarians) during the late
cretaceous period (60-95 million years ago). Flints are concretions
that grew within the sediment after its deposition by the
precipitation of silica; filling burrows/cavities and enveloping the
remains of marine creatures, before dehydrating and hardening into
the microscopic quartz crystals which constitute flint.
Where can you find flint?
Flint is found in areas with chalk bedrock, this is because
flint formed within the sediment that later became chalk. At this
point it's worth noting that the chalk was formed in much larger
quantities from the remains of microscopic calcareous plankton,
particularly Coccolithophoroid algae, whose tiny skeletons are known
as coccospheres. Upon death, trillions of these microscopic
skeletons rained down on the sea floor, accumulating in layers of
white ooze, often falling apart into their component pieces
(coccoliths). This white ooze later hardened into chalk.
Over tens of millions of years, continental movements relating
to the formation of the Alps resulted in gentle folding, uplift and
erosion of the chalk, forming familiar geological structures such as
the South Downs of Southern England. Over time the chalk hills have
been eroded, exposing and depositing flint nodules as they retreat.
These flints then accumulate to form the flints seen in fields and
the characteristic flint pebble beaches along the coast.
Displacement of these flint deposits also occurs due to
long-shore drift, resulting in flint beaches many miles from the
chalk source. Recent ice ages have played their part, as former
glaciers have transported thousands of tonnes of material to new
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Left: A large
selection of flint fossil echinoids found at
Right: A fossil bivalve visible on the surface of
a flint nodule from
A wide range of fossils can be found within flint nodules,
indeed in many instances the nodule itself is in fact an internal
mould of a sea creature.
The silica accreted around the nuclei of organic remains and
biogenic structures, such as the remains of sponges or the burrows
of crustaceans. Therefore the flint fossils you find reflect the
diversity of life and the activities of creatures on the seafloor at
that time. Among the most commonly found flint fossils include
sponges, echinoids, shells and of course trace fossils i.e. burrows.
Pseudo flint fossils
Flints nodules are often mistaken for fossils. Since
Discovering Fossils was launched we've received countless emails
from visitors claiming to have discovered a variety fossilised
objects. Among the best includes a 'fossilised human foot', a 'man's
arm' and a 'goat trotter'! None of these were in fact
fossils strictly speaking, instead what they had discovered were
flint nodules that had formed to resemble such objects (pseudo
However it is likely that these objects were trace fossils, such as
lobster burrows. In these instances the silica would have filled
and overgrown the creature's burrow, thus forming a flint copy of
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
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