Bexhill Quarry and Brickworks first began in the 1890s, when clay shale deposits were worked, until the early 1940s. In 1998 the site was closed due to competition from other brickworks and quarries. The quarry has now filled with water, leaving a lake that has to be seen to be believed.
The area and sheer wall that you see are made up of mixed rocks. According to Wells & O’Brien (1994) the coal measures include sandstones (made from volcanic rock fragments), carbonaceous siltstone, shale, mudstone, coal and clayey siltstones. Also clayey ironstone and infrequently oil shale and limestone can be found. Apparently tree stumps remaining in their growth position have also been found, though these have become carbonised (coal). The coal layers themselves are thin (millimetre scale) to occasionally thick (30-40cm) in the Southern Basin this is part of whats known as the Walloon Coal Measures.
The coal in the measures is formed from peat that grew in a moist but temperate environment during the early to middle Jurassic in this area (smack in the middle of the age of the dinosaurs). The depositional environment appears to have been mainly flood-plain and meandering stream environments. Boggy mires forming the peat were common, but layers of volcanic ash from occasional volcanic eruptions from close by are preserved. This makes some of the coal seams high in ash content which reduces the quality of the coal. The environment was thought to be reflective of a period of high sea level.
The lake that you see in front of you is made up of flooding of the pit, and is now dominated by ground water infriltration. The water gets its colour from the high levels of metals and minerials, some of which include aluminium, copper, manganesium and zinc. The levels of these metals and minerials are high, they are still within swimming guidelines for humans. The water is actually pristine in regard to nutrients and bacteria. The origin of the acidity and metals is due to an acceleration of natural processes similar to the acid sulphate soils in this region releasing acid and metals. This causes a decline in the Faecal coliforms and Cyanobacteria, which can cause the 'cloudyness' and murky colour of some waterways.
Comparing water qualities to other areas.
Bexhill Quarry
Ph 4.1
Acidity -mg/litre 13
Faecal coliforms - cfu/100ml <10
Cyanobacteria (blue-green algae) - cells per ml 180
Lake Ainsworth
Ph 5.8
Acidity -mg/litre 7
Faecal coliforms - cfu/100ml 60
Cyanobacteria (blue-green algae) - cells per ml 1140
Wilson River, Lismore
Ph 7.65
Acidity -mg/litre 3
Faecal coliforms - cfu/100ml 30
Cyanobacteria (blue-green algae) - cells per ml 360
How to log this Earthcache
Please email the CO your answers to the following questions.
(No need to enter the water or past the fenced off area)
Q1. - Looking toward the sheer rock wall facing you, do you see virtical or horizontal layers?
Q2. - (a) How many types of layers do you see (approx) (b) What colours of rock do you see? (c) What type of rock make up this wall?
Q3. - (a) What colour is the water? (b) How do you think the water has become this colour (include the mineral type)
Q4. - Is this water acidic or alkaline on the Ph scale? What evidence do you rely upon to support your answer?
* Photo's/Selfies of the area are optional but always welcomed.
I hope you have enjoyed learning about this interesting rock wall and pool.