How the Mosses formed
The area around the Mosses, called the
Meres and Mosses Natural Area, is unique. The whole range of the progression
from the open
water of the meres through to mossland can be
seen. In deep water, only algae and floating plants like water lilies can
grow. In shallower valleys or along mere fringes, swamp plants like reeds
and bulrush colonise, their remains filling the water in until fen plants
like sedges, rushes and bur-reed, then wet alder and willow carr woodland
can invade. Once fen peat builds up above the influence of nutrient-rich
ground water, Sphagnum bogmoss can take over, rapidly accumulating
spongy peat, to build up a domed raised bog.
During the last glaciation, ice sheets from the Welsh mountains and the
Pennines bulldozed the landscape, pounding rocks into clay and sand and
gravel. As the climate warmed, they dumped their burden up to 50 m deep in
this area. Melting ice water cut a flat-bottomed valley into these deposits,
running south-west from Fennís Bank. Clay ridges to the south partly blocked
the valley and a huge wetland formed.
peat first began to form on the poorly
draining clay in the southern half of
at Wem and Bettisfield Moss c. 8500 - 7500 BC, blocking the
valley even more and causing water-logging upstream. Through time the bog
spread north-eastwards, over the clay of Whixall Moss at c. 6000 BC, the
sands of Fennís Moss at c. 5000 BC, the higher sands of N E Fennís Moss
later, the outer area of Whixall Moss c.
2500BC and then outwards all round the
bog at c. 500 AD. The deeper peat on clay shows the full Ďhydroseralí
development from open water to bog, whereas the shallower peat on sand shows
the swamping of heath or the dense Mercian wildwoods.
Sand or Clay
Lake deposits 'coal'
Reed swamp 'black' peat
Fen 'black' peat
Bog ' grey' peat
Bog 'white' peat