the chert was formed when silica-rich water from volcanic springs rose and rapidly petrified the early terrestrial ecosystem "in situ". organisms are petrified that way by hot springs today, although that quality of preservation has not been found in recent deposits. hot springs, with temperatures between , were active; the water had probably cooled to under before it reached the fossilised organisms. the deposits are interbedded with sands, shales and tuffs, which speaks of local volcanic activity. deposition was very rapid.