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Academic Staff

Dr Alan Channing

Terrestrial hot spring deposits provide spectacular insights of ancient ecosystems at key moments in the evolution of life. One such deposit, the Rhynie Chert of Aberdeenshire, Scotland, formed 400 million years ago as water from hot springs flowed across a landscape inhabited by early land plants. Silica dissolved in the hot spring waters preserved the local ecosystem as opaline silica permineralised and encrusted organisms and created a silica sinter deposit. The plants, microbes and animals of the Rhynie Chert now represent our most detailed evidence of the functioning and interactions an early terrestrial ecosystem. My research has focused on how and why organisms become fossilised in hot spring environments and if the processes that influence an organisms potential for preservation create biases in the fossil record.

PhD Research

Dr Alan Channing

Collecting naturally silicified stems
of geothermal wetland plant
Eleocharis rostellata, Yellowstone
National Park. 

I use the active hot spring environments of Yellowstone National Park as analogues for ancient systems. As a PhD student I conducted plant taphonomy experiments that investigated patterns of plant preservation/decay and fabrics and processes of silica deposition. These revealed that colloidal processes dominate silica deposition within plants as silica precipitates most readily from hot spring waters as opal. This takes the form of micron-scale spheres which are subject to colloidal forces such as flocculation, coagulation and gelation. These produce very distinctive networks of silica particles and solid silica films and blocks which stabilise plant tissues against collapse (Channing & Edwards 2004).

My experiments also revealed that protracted periods of water-logging are required for high quality preservation of plant tissues. In Yellowstone this is most often achieved in cool wetland habitats that form at the margins of hot spring areas (Channing 2003 LINK). I hypothesised that the excellent preservation of large numbers of plants at Rhynie occurred in a geothermal wetland (Channing et al 2004) as most hot spring environments only support sparse vegetation whilst geothermal wetlands support relatively lush vegetation which live and die immersed in silica rich hot spring waters.

Dr Alan Channing
Opal-A microsphere network and
blocky silica filling intracellular sites
in cells of the wetland plant
Eleocharis rostellata. 

Geothermal wetland, Elk Park, Yellowstone National Park, colonised by the halophytes Eleocharis rostellata and Triglochin maritimum.

Current Research

Currently, I am investigating active geothermal wetlands of Yellowstone. My research has a broad focus but the principal aim is to investigate the ecophysiology of the Rhynie Chert plants via analogy with vegetation of active geothermal wetlands. In order to achieve this I am:

  • Attempting to characterise the physical and chemical environment of active wetlands using data-logging equipment and probes that measure basic parameters which affect plant colonisation and growth including -conductivity, redox, pH and temperature.
  • Dr Alan Channing

    Geothermal wetland, Elk Park,
    Yellowstone National Park, colonised
    by the halophytes Eleocharis
    rostellata and Triglochin maritimum. 

    Analysing water samples to reveal concentrations of nutrient, beneficial and phytotoxic elements available to plants and concentrations of silica available to fossilise vegetation.
  • Investigating the sedimentology of active Yellowstone geothermal wetlands and fossil examples in Queensland, Australia and Santa Cruz Province, Patagonia to provide models that can be tested against the Rhynie Chert.
  • Conducting taphonomy experiments which investigate patterns of plant decay/preservation and silica deposition which can be compared to other hot spring environments including vent pools, sinter aprons and run-off streams. These will allow comparisons of plant preservation potential between high and low temperature and wet and dry environments which it is hoped will reveal environment specific taphonomic fabrics.

Dr Alan Channing

Top Left: Latex cast of silica encrusted coot.
Bottom Left: SEM and Light microscope
images of silica encrusted feathers. Top
Right: Ice formed by the freezing of silica
rich hot spring water contains pockets of
gel like silica particulate. Bottom Right:
Morphology of cryogenic silica particles
formed in brine pockets in frozen hot
spring fluid. 

Other Areas of Research

Interactions of vertebrates and hot springs (Channing et al 2005).Interactions of hot springs and sub-zero environments (Channing & Butler 2006).