1870.] HUNT — ON GEOLOGY OF EASTERN NEW ENGLAND. 205 



in the valley of the St. Lawrence near Montreal ; where, on the 

 island of St. Helen they rest unconformably on the Utica slate, 

 and at Beloeil Mountain, near by, on intrusive diorites, which 

 there break through the shales of the Hudson River group. 



The relations of this Terranovan series to the porphyries and 

 diorite rocks which, in New Brunswick, have been called Cam- 

 brian and Huronian by Mr. Matthew (first distinguished by him 

 as the Coldbrook group), yet remains to be determined. These 

 rocks are found near to the city of St. John resting directly on 

 what has been regarded as Laurentian, and are overlaid by the 

 uncrystalline schists which contain the primordial ftiuna now 

 so well known by the descriptions of Prof. Hartt. Rocks which I 

 regard as identical with the same Coldbrook or Cambrian group, 

 are found along the coast of New Brunswick, and constitute the 

 diorites and porphyries of Eastport, Maine. They appear more- 

 over to be the same with those met with near Newburyport, and 

 Salem, Lynn, and Marblehead, Massachusetts. Farther research- 

 es about Passamaquoddy Bay, where the mica-slates are found not 

 far removed from these porphyries, will probably enable us to 

 determine their relation to each other. 



It will be remembered that Giimbel has found, in Bavaria 

 beneath the oldest fossiliferous clay-slates, a mica-gchist (and * 

 hornblende-schist) series, reposing upon the Hercynian o-neiss 

 which contains crystalline limestones, with graphite, serpentine 

 and Eozoon Canadense, and which he has identified with the 

 Laurentian of North America. He distinguishes beneath this a 

 great mass of red gneiss, apparently without limestones, to which 

 he has given the name of the Bojian gneiss. It will however be 

 remembered, that in his studies of the Laurentian system on the 

 Ottawa, Sir William Logan has shown that this immense series 

 (his Lower Laurentain), some 20,000 feet in thicknesss, includes 

 four great masses of gneiss and quartzite, divided by three lime- 

 stone formations, and that it is in the uppermost of these, which 

 is, in some parts, 1500 feet thick, that the Eozoon Canadense jia.s 

 been found. Some of the lower gneisses of this vast system 

 may very well represent the Bojian of Giimbel, who has not reco"-- 

 nized in Bavaria either the Labradorian (Upper Laurentian) or 

 Huronian series. (See Giimbel on the Laurentian of Bavaria, 

 trAi: slated and published in the Canadian Naturalist for December 

 1866). Comparative studies of this kind should not be neglected 

 in the investigation of our American rocks. 



