Matthew — Post-Glacial Faults in New Brunswick. 501 



method has recently been developed by Prof. Michelson who 

 in order to obtain spectra of difficultly volatile metals in vacuo, 

 adopts the ingenious expedient of rotating the interrupter 

 wheel in a Torricellian vacuum by means of a long shaft pass- 

 ing up through the mercury column.* A somewhat similar 

 method has also been quite independently used for obtaining 

 spectra of different metals in air by Messrs. Crew & Tatnall.f 



It would seem to be a particularly promising one for the 

 investigation of the infra red lines of the metals and alkali 

 earths. 



University of Chicago, October, 1894. 



Art. LXYII. — Post-Glacial Faults at St. John, N. B. ; 

 By G. F. Matthew, D.Sc, F.K.S.C. (With Plate XL) 



Nowhere, so far as the writer is aware, has there been put 

 on record any account of disturbances in post-glacial times, of 

 the rocks along the lines of faulting, in this North-eastern 

 part of America. There are numerous places in all parts of 

 this region where the removal of drift deposits allows of the 

 inspection of the glaciated surfaces of the rocks, and had such 

 faults been common it would seem highly probable that their 

 presence would long ere this have been noticed. This thought 

 induces the writer to give a brief sketch of the numerous small 

 displacements, produced since the glacial period that have been 

 observed in the rocks in and near St. John, N. B., Canada. 



Numerous proofs of post-glacial disturbances of the earth's 

 crust are visible in the slate rocks which form a large part of 

 the rocky foundation on which St. John is built. These are 

 true post-glacial faults. They are well shown along the hill- 

 side south of " The Yalley " in that city. This valley is an 

 east to west depression in the northern section of the thickly 

 inhabited part of the town. 



The rocks along the southern slope of this valley consist of 

 the fine, dark-colored shales or slates of the Bretonian or Upper 

 Division of the St. John Group ; which by their fine grain and 

 uniform texture, are well adapted to preserve the sharp grooves 

 and striae impressed upon them in glacial times, by the moving 

 ice. 



The faults visible along this hillside belong chiefly to a sys- 

 tem having approximately a N.E. to S.W. course, and a hade of 



* Univ. of Chicago, 1893-4. Results not yet published, 

 •j- Phil. Magazine, vol. xxxviii, p. 379, October, 1894. 



