METAMORPHISM OP LIMESTONE. 
401 
nied by Captains Strajefski and Popoff, and our former companion Karpinski, we 
embarked in small canoes at the station of Kakvinski, and glided down the tor- 
tuous and rapid stream. We found the whole gorge to consist of rapid undulations 
of limestone, which thrown into a number of saddles and troughs, is occasionally 
much dislocated. Associated with it, we observed alternations of bedded trap- 
psean rocks like those near Bogoslofsk. The limestone is usually of a dark grey 
colour with white veins, but in the vicinity of the bedded trap, as at Bogoslofsk, 
it is red and compact. Wherever it is cut through by igneous rock of directly 
intrusive character, the limestone is highly altered ; and we met with one example, 
where, in absolute contact with a dyke of greenstone porphyry, it had been con- 
verted into a pure white, saccharoid, granular marble, which crumbled away under 
the touch. In short, this descent of the Kakva would satisfy any one, however 
opposed to the doctrine of metamorphism, that there can be no more certain method 
of accounting for the crystalline condition of limestones in contact with eruptive 
igneous rocks, which at certain distances therefrom are unaltered and contain or- 
ganic remains. The limestones are thrown about in various flexures to the east and 
west, whilst the dominant strike, from north and by east to south and by west, is 
very clearly maintained. For long spaces where the limestone is not absolutely 
saccharoid or crystalline, it is often compact, amorphous, and without distinct 
traces of bedding, and constitutes picturesque cliffs. One of these, called by the 
boatmen “ Bielaya-kamen,” or the white rock, particularly attracts attention, when 
it peers out from umbrageous thickets and rich vegetation. 
Amid such strata we had at first little hope of discovering fossils, but here and 
there we were fortunate enough to collect an adequate number to satisfy us of the 
age of the rock. Even in the associated bedded trap, which very much resembled 
“ schaalstein,” we found corals similar to those which we had collected in a some- 
what similar rock upon the Lahn in Nassau ; such as Favosites polymorpha, F. 
rctmosa, and Stromatopora concentrica. These fossils, which with the Terebratula 
reticularis or prisca and a plicated Terebratula were also found on the vertical 
and weathered faces of the limestone, led us naturally to believe, that the greater 
portion of this rock may be considered Devonian. 
We also detected, however, in a limestone, one of the Pentameri, common to 
the underlying rock of Bogoslofsk 1 . Our belief therefore is, that in the undula- 
1 M. Rose mentions the occurrence of a trilobite in this limestone of the Kakva, which was supposed to 
he the Calymene Blmnenbachii. 
