ABRAHAM GESNER — REVIEW OF HIS SCIENTIFIC WORK. l! < 



llie Grni/icacke Systein. 



In classifying the rocks in the soutliein part of New Bruns- 

 wick, Dr. Gesner at first divided them into the three simple 

 classes recognized by the earlier geologists, viz.: The Granite and 

 other crystalline rocks ; the Transition series ; and the Second- 

 ary formations. Thus the transition rocks are the more or less 

 altered rocks of the metamorphic massif or complex of southern 

 Xew Brunswick ; and include all the terranes from the Lauren- 

 tian to the Devonian. Dr. Gesner, howevex% proceeded to improve 

 his classification year by year as his survey progressed. In the 

 second year of his survey he made some important discoveries of 

 fossils near St. John which led him to conclude that the slates 

 and graywacke of the transition rocks crossing the harbor of St. 

 John, and at the entrance of the river of that name, were to be 

 classed with the " Silurian group of Mr. Murchison."* This 

 remark certainly applies to the slates and graywacke, and appears 

 also to include the Hmestones north of them, for he asserts that 

 the fossil shells found in the slates were afterwards met with in 

 the limestones.! His opinion of the age of the plant-bearing 

 beds is very clearly expressed (page 12) where he says "these 

 plants belong to the first classes of vegetables that ever flourished 

 on the earth. They * * are evidently far more ancient than 

 those which afford bituminous coal." 



Still extending his observations on the rocks along the coast. 

 Dr. Gesner, in the third year of his work, found reason for a 

 further division of the strata of the transition complex. In 

 examining the rocks from Cape Mispec eastward he found an 

 older and more altered set of beds, which, in relation to the 

 Silurian rocks above mentioned, were primary,! and further he 

 found that this older set had a reversed dip§ as contrasted with 

 the " Silurian." In these apparently older and lower strata, no 

 organic remains were found, and further they were harder, were 

 more replete with quartz veins, and talc and chlorite were asso- 

 ciated with them. Dr. Gesner therefore concluded that thouyh 



* Second Report, p. 3. 



+ Second Report, p. 8. This observation, however, is open to question, as these 

 limestones are older than any rocks in which moUusca or molluscoida have been 

 found. 



t Third Report, p. 3. § Third Report, p. 7. 



