164 Mr Haiclinger on the occurrence of 



Fig. 1. Fig. -2. 



According to the form, the radiated portions and the crystal^ 

 must have heen originally arragonite or prismatic lime-haloid. 

 When, however, these are broken in two, there is no trace of 

 th e crystalline structure and conchoidal transverse fracture of 

 that species, but, on the contrary, we find a combination of in- 

 dividuals of the rhombohedral lime-haloid or calcareous spar. 

 The previously formed crystals of arragonite, therefore, have 

 been converted into calcareous spar by a subsequent supple- 

 mentary process. In conformity to the experiments of Gustav 

 Rose, we may assume that the pseudomorphosis of arragonite 

 in the wood has taken place during a high temperatm'e, while 

 that of calcareous spar in arragonite has occurred at a low tem- 

 perature. The deposition of the basaltic tufa on the east 

 side of the basaltic outburst, the flowing in of the boiled wood 

 between the layers, occurred during a high temperature, while 

 the waters found an outlet to the east, at the same period of 

 time in which, by means of the elevation of the land to its 

 present height, the valleys of the Elbe and Eger throughout 

 their whole extent, burst across the solid land. The forma- 

 tion of the crystals of arragonite occurred during the first por- 

 tion of the period of cooling ; and the conversion of the arra- 

 gonite into calcareous spar during the second portion, during 

 which circimistances more nearly approached the state of mat- 

 ters at the present day, and which is perhaps not yet arrived 

 at a termination. As in other places in the neighboiu^hood, for 

 example at AValtsch, arragonite is contained in a similar rock, 

 without being converted into calcareous spar ; further observa- 

 tions are necessary to decide, if rapid evaporation on one side 

 and moist pressure on the other were the circumstances ^vhich 

 produced this difiference. 



Elbooev, 8.*') /«»' 1838, 



