Dr Louis Emery recently completed his PhD project that looked at processes of mineral precipitation, tufa fabric development and fossilization at South Wales' version of Yellowstone National Park. No hot springs or geysers here, but instead tufa aprons developed in an area where water flowing from springs at the base of lime-kiln waste tips has exceptionally high pH creating (arguably) Wales' most extreme habitat.
Louis thesis is available here
:Emery, L. 2013.
Extreme environments: tufa formation at
high pH from lime kiln waste, South Wales.
Invasive tufa deposits on Foel Fawr, South Wales are forming from lime kiln waste deposited from
the 18th century until the 1950s. The tufa deposits are unusual in their anthropogenic origin and
form the largest site of this type in the UK. At emergence pH is extreme (>11) and this
consequently generates significant pressure on organisms living in and around the system.
Morphologically, the calcium carbonate tufa deposits are similar to those formed in other extreme
environments (e.g. hot springs, caves), forming many of the same features (e.g. terraces, rimpools,
pisoids, stalactites). By identifying and mapping tufa facies at Foel Fawr, the spatial distribution of
these facies has been directly compared to these potentially analogous environments. Analysis of
the fabrics associated with each facies highlights the importance of physico-chemical precipitation
in the system; proximal facies are dominated by abiotic fabrics, while distal and marginal facies
show an increasing degree of biological influence. This process is comparable to the partitioning of
fabrics and facies observed in hot spring systems, however, the role of microbes in precipitation is
apparently less important on Foel Fawr.
The present day extreme chemistry of the site selectively excludes organisms and generates a
partitioning of biology. Hydrochemical monitoring of the site reveals that the extreme pH of the
system is in decline. The recession of the extreme hydrochemistry is confirmed by colonisation of
previously excluded organisms and allowed the physical decay of the site. Fabrics preserved within
the deposits support the suggestion that the extreme environments were previously much more