PALEOZOIC TERRANE BENEATH CAMBRIAN. 



43 



the ease with which the fossils can be recog- 

 nized, but the chemical changes which took 

 place in the Etcheminian sediments, as well as 

 different conditions existing at the time of 

 their entombment, have tended to obliterate 

 the Etcheminian organisms while the Cambrian 

 have remained. 



In the base of the Cambrian the Hyolithoid 

 shells and the Foraminifera have preserv^ed the 

 substance of their tests, but in the older ter- 

 rane this has been replaced by glauconite or, 

 some other mineral substance ; so that in many 

 cases the structure is gone and only a cast of 

 the fossil remains. Still there is no evidence 

 that the Etcheminian sediments were consol- 

 idated before the deposition of the Cambrian, 

 as. they have given no fragments to the latter, 

 and apparently have furnished only mud and 

 sand, for the building up of the Cambrian 

 layers. 



Section North from St. John. — Although 

 there is but slight evidence in the condition of 

 the sediments of the greater antiquity of the 

 Etcheminian, and the unconformity existing 

 between it and the Cambrian, this break be- 

 comes manifest when the distribution of the 

 two is traced in the field, for then we find 

 that the older terrane was entirely eroded from 

 large tracts of country before the deposition 

 of the newer. The accompanying section, 

 taken along a line from the harbor of St. John 

 northward, (Fig. i) shows an instance of such 

 erosion. In the city of St. John a belt of 

 Etcheminian strata crosses the southern end of 

 the city, being exposed along the southern 

 side of the basin of Cambrian rocks on which 

 the city is built. On the north side of this 



O 3 



S o 



O 3 



2 Cu 

 O I— I 





