434 Scientific Intelligence. 



eating dinner one bright day, they heard a snapping noise. The 

 rock in the bed of the quarry was ripping. The disturbance 

 started at the lower end, traveled up the river, and ended in a 

 wheel-pit fifty feet square and four feet deep. It required sev- 

 eral seconds to make the trip, and shook up the "quarry chips" 

 that covered the bottom of the quarry to the depth of about a 

 foot. Later, when the covering of the chips were removed and 

 the quarry cut deeper, it was found that the first eight inches of 

 the rock was broken by a clean fracture, but below that, was 

 much crushed. How far down the crushed condition extended is 

 not known; the quarry was made two feet deeper, and crushed 

 rock was still in sight. The direction of the crack was N. 45° E. 



When the several cases of fracture described above, all of 

 which occurred in the compact Galena limestone of the Fox River 

 valley, are considered together, it becomes clear that the weight 

 of the clay plain had nothing to do with their production, for 

 some of them run parallel with the river and the high clay banks, 

 and others make high angles with them. And, further, there 

 is no parallelism among the cracks themselves. The times of the 

 year and other conditions under which the disturbances occurred 

 make it impossible to assign a common local cause for them, and 

 it is as difficult to point out a separate cause for each. It seems 

 evident that the cause of the fractures is a condition of the rock 

 itself; and that in this region it is suffering compression in all 

 directions. The local character of the disturbances is well illus- 

 trated by the fracture at the Combined Locks, where at one end 

 there were crushing, uplifting and faulting, and less than 125 feet 

 away there is nothing but a simple fracture. The direction of 

 fracture seems to be determined, not so much by preponderance 

 of pressure in a particular direction as by the artificial relief 

 given in each case. The local conditions, perhaps even including 

 barometric disturbances, seem to furnish nothing but the occa- 

 sions for the action of the general cause. The facts are in har- 

 mony with Gilbert's theory that the superficial strata have ex- 

 panded in consequence of their rise in temperature since the close 

 of the glacial period. But more data are needed for a demonstra- 

 tion. 



Lawrence University, Appleton, Wis., Jan. 10, 1891. 



2. Bulletin of the Geological Society of America, Vol. II. — 

 The papers read at the December meeting, already published, 

 include the following : C. L. Herrick, on the Cuyahoga Shale, 

 and the problem of the Waverly ; G. F. Becker, on the structure 

 of a portion of the Sierra Nevada ; Ed. "V. DTnvilliers, on the 

 Navassa phosphate deposits; A. Winchell, a last word with the 

 Huronian ; C. W. Hayes, on the overthrust faults of the Southern 

 Appalachians ; Robert Bell, the nickel and copper deposits of Sud- 

 bury District, Canada, with an appendix on the silicified glass- 

 breccia, by G. H. Williams ; Geiger and Keith, on the strucure 

 of the Blue ridge near Harper's Ferry; G. M. Dawson, Geological 

 structure of the Selkirk range; G. F. Becker, on Antiquities 



