NOME VIII. KOLLANITB. 119 



variety, and pleasing accidents, not observable 

 in any other rock, seems confined to the district 

 of Hertfordshire above mentioned. 



If the term pudding-stone be restricted to 

 what the Germans would call an agglomerated 

 substance, it may even be doubted whether it be 

 properly applied in the present instance ; for it 

 is not only clear, as Patrin has remarked, that 

 the pebbles never have been rolled ; but, from an 

 accurate and minute examination, that the whole 

 is an instantaneous composition, a kind of dis* 

 turbed crystallisation, like granular quartz ; or, 

 as in the stones called glandulites by Saussure, 

 as containing nodules of a finer or coarser grain. 

 It would seem that an intrusion of iron and clay, 

 or what is called jasper, has imparted this pecu- 

 liar appearance, as iron often inclines to the 

 pisiform and fabiform. Or it may be that in a 

 siliceous sediment the iron asserted its predomi- 

 nance and affinities, to assume these singular and 

 beautiful forms*. But geologists might compose 

 whole treatises on this rock alone ; which may 

 be as important towards a theory of the earth, 

 3,8 Saussure found the noted pudding-stone of the 



* On the influence of iron in such formations, see Collini's inge- 

 nious little work on the Agates of Oberstein. Manheirn, 17?6, 

 12mo. p. 126, seq. 



