The formation of the clay minerals can be divided into three different stages in the tuffs.From theCambridge English Corpus
The results show that the fluid compositions varied significantly between the different tuffs.From theCambridge English Corpus
Toward the inlet of the conduit, the capstones consisted of extremely heavy, river-worn, shaped slabs oftuff.From theCambridge English Corpus
From the data available on thetuffsamples so far, the recognition of species has proven problematic due to the fragmentary nature of the fossils.From theCambridge English Corpus
Since the chemical composition of the primary tuffs likely reflects their source material, the tectonomagmatic derivation of the volcanic ashes can be deduced.From theCambridge English Corpus
Capstones also made of volcanictuffcovered the conduit for the length of its course, although differences in how the capstones were worked are apparent.From theCambridge English Corpus
These two tuffs could have had the same parental magmas than the other tuffs and associated basalts.From theCambridge English Corpus
The sequence comprises alternations of coarsetuffunits that fine upwards and thinner lapilli-richtuffhorizons.From theCambridge English Corpus
In the massive tuffs, vitric to crysto-vitric varieties show delicately shaped glass shards and broken phenocrysts of euhedral quartz, plagioclase, muscovite, orthoclase, zircon and ilmenite.From theCambridge English Corpus
More rarely clasts of streaky flow-banded or parataxitic material occur, derived from earlier welded tuffs.From theCambridge English Corpus
Simultaneous eruption of ash-flow tuffs resulted in a sequence of interbedded tuffs, sedimentary breccias and andesitic lavas.From theCambridge English Corpus
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