habitats. But I digress. In marshes, decomposition is partial and largely anaerobic as it is
under water, and of course peat or even coal could form in these conditions, given time.
The anaerobic conditions lead to several compounds rich in hydrogen, many of them
gaseous, being formed.
Marsh gas, also called natural gas, is mainly methane, a simple compound of carbon and
hydrogen, which readily burns if ignited (as in a gas cooker or boiler) with a very pale
yellow or bluish flame usually hard to see at all except at night. In marshes, soft tissues
from plants or animals arc gently half-rotting, and as they break down they produce many
gases, one of which is called phosphine, a simple gaseous compound of phosphorus and
hydrogen, and also ammonia, a simple gaseous compound of nitrogen and hydrogen.
Phosphine and its close relatives ignite spontaneously in warm air. On a summer night
the marsh gases would seep out, and the phosphines would ignite, consuming the more
abundant methane and ammonia as well. When phosphines burn they make a white smoke
which hangs in the air for a while, so the pale flickering flame with white smoke in it is
the will-o'-the-wisp. Poking with sticks to disturb the mud under a pond usually releases
lots of the gases as bubbles, but in the daytime any flame is hard to see, and on a cold day
it would not ignite anyway.
Incidentally, methane is a serious greenhouse gas, much worse than carbon dioxide, and
produced in large quantities by the complex guts of ruminants. The human liking for
meat, especially beef, has led to a huge increase in methane in the air. Did you know that
the energy obtained by burning the methane from just one cow every day is enough to
supply the daily energy needs of four homes? So the answer to both the energy crisis and
the global warming is for home-owners to get together and collect the methane from a
shared cow. Next time I see a cow in a field with a large balloon at its anus, I shall know
you have been at work!
In the New Year the weather became milder, but with wind and some rain. But fortunately
not enough rain to make our rivers flood as they did in Carlisle, nor with wind gusts of
120mph as they had in Northumberland. We can also be thankful that Essex is not on a
major tectonic plate boundary, so we do not often have volcanoes or severe earthquakes
or tsunamis. But we do have a slightly sinking land mass, accompanied by rising sea
levels. In mid January they were talking about having to do more flood defences for
London as the Thames Barrier will soon not be enough. They are saying that some of the
'empty' land in North Kent and South Essex should be available as emergency flood
plain. At the same time, this plan for filling the Thames edges with housing in the Thames
Gateway project seems more and more crazy. Then in February an association of insurance
companies reported that new houses built on flood plains would be uninsurable and thus
unsaleable. When will somebody in the Government wake up to the nonsense of it all?
Meanwhile life is stirring outside. In my garden is a flowerpot with Glabrous Whitlowgrass,
given to me by another botanist as seed last summer. The plants are in full flower just
now (late January), at the same time as the Snowdrops and Winter Aconite. But don't
8 Essex Field Club Newsletter No. 47, May 2005