Lincolnshire is flat! .. No
it’s NOT!
Remarkable as it may seem to those people who
believe that Lincolnshire is as flat as the ocean, there really are
hills in the county and lots of them too.
The Lincolnshire Wolds comprise
of a series of low hills and steep valleys underlain by calcareous
(chalk and limestone) and sandstone rock, laid down in the
Cretaceous period.
The characteristic open valleys
of the Wolds were created during the last ice age through the
action of glaciation and melt water.Geographically, the Lincolnshire Wolds are a
continuation of the Yorkshire Wolds which run up through the East
Riding of Yorkshire, the Wolds as a whole having been bisected by
the tremendous erosive power of the waters of the
Humber.
Most of the Lincolnshire
Wold’s are made up from layers of chalk, which is one of the
best known of all rocks, recognisable for its white colouration in
striking land features such as the White Cliffs of Dover in Kent
and the Severn Sisters East Sussex. Chalk has been exploited by man
for thousands of years for both its physical and chemical
properties and has fascinated scientists for centuries because of
the fossils it contains and its geological story.
What is Chalk?
Chalk is formed from lime mud, which accumulates
on the sea floor in the right conditions. It is then transformed in
to rock by geological processes: as more sediment builds up on top,
and as the sea floor subsides, the lime mud is subjected to heat
and pressure which removes the water and compacts the sediment into
rock.
If chalk is subject to further heat and pressure
it becomes marble.
The lime mud is formed from the microscopic
skeletons of plankton, which rain down on the sea floor from the
sunlit waters above. The Coccolithophores are the most important
group of chalk forming plankton. Each miniscule individual has a
spherical skeleton called a cocosphere, formed from a number of
calcareous discs called coccoliths. After death, most coccospheres
and coccoliths collapse into their constituent parts. Most chalks
formed during the Cretaceous period, between 100 and 60 million
years ago, and chalks of this age can be found around the
world.
Chalk is not as white as it
seems!
Chalk is white because it is formed from the
colourless skeletons of marine plankton, and it is free from
impurities because sea levels were very high, so there was little
land exposed to supply other sediments to mix in with it as it
formed.
The Cretaceous sea floor was also very active so
any organics were quickly broken down. The result was a very pure
lime mud, formed almost entirely of planktonic skeletons.
However, At Redhill Earth Cache, not
all the chalk is white. The area comprises 4 acres of steep chalk
escarpment grassland, and a disused quarry with a famous exposure
of Red Chalk, which is rich in fossils, particularly belemnites and
brachiopods.
Below the Red Chalk there is a
considerable thickness of Carstone, here and a coarse pebbly
sandstone. Above it lays a thin capping of the white Lower Chalk.
The exposure of the Red Chalk is a formation that only occurs in
Norfolk, Lincolnshire and Yorkshire. From the Earth cache area, the
next visible area of Red Chalk is at Hunstanton in
Norfolk.
Red Chalk is caused by iron oxide (rust) within
the chalk which discolours it. This is very rare occurrence and
you’re lucky to see it. Please respect this area and stay on
the roadsides when possible.
To
claim this earth cache you must do the
following;
At
the bottom of the road pull in at coordinate N53.18.230 W000.06.656
and take an elevation reading in metres. Now take another elevation
reading near the car park area at N53.18.471 W000.06.187, again in metres. Now calculate the height of the
scarp deducting the lower reading from the
upper.
Email the height difference of the two
measurements.
What is the chemical formula for
chalk?
Name the two rare butterflies/moths found at this SSSI
location.
Take a photo at the following coordinate (It’s on the
roadside, so no need to climb up the bank side) N53.18.446 W
000.06.267 showing yourself with your GPS and the red chalk in the
background.
The posted
coordinates (at the top of this page) are of the position required
to take your photograph.
Please go to
N53.18.474 W000.06.173 for a safe place to park your
vehicle.
You ,may claim your find
immediately. Please upload your photos at the same time.
Then email your answers via my profile
above. I will confirm if they are
correct.
Under no circumstances should you post the answers in your log
or post photographs of the answer. You must physically visit this
cache in order to log it, (I regret that I will have to delete logs
that do not meet these requirements). When you email the answer then please
remember to release your email address to enable us to
reply
.
This cache is The Imp's 100th Cache.
The Imp is a Platinum Earthcache
Master.
----------------------------------------------------------------------------
This Earth
Cache has been granted with the kind permission of The Lincolnshire
Wildlife Trust. www.lincstrust.org.uk
Charity
no. 218895. Registered in England,
no. 461863. Registered offices: Banovallum House, Manor House
Street, Horncastle, Lincs LN9
5HF.
Lincolnshire
Wildlife Trust, safeguarding wildlife and wild places in
Lincolnshire and promoting understanding and enjoyment of the
natural world from the Humber to the Wash.
Are
you a member? Join today at www.lincstrust.org.uk