324 



SCIENCE. 



[Vol. II., No. 31. 



Clay pebbles from Princeto-vyn, Minn. 



BY N. It. WINCHELL OF MINNEAPOLIS, MINN. 



This paper was accompanied by an exhibition of 

 specimens. The pebbles were of varions shapes and 

 sizes, several of them somewhat cylindrical. Out- 

 side, tliey are composed of fine sand and gravel ; 

 inside, they consist wholly of a fine sedimentary 

 clay, such as is deposited by standing water, and 

 contain no interior pebbles. Professor Winchell had 

 compared these with pebbles found in till-deposits, 

 and with various others, without finding any thing 

 exactly similar. 



Professor Newberry examined the pebbles, and ad- 

 mitted that they were not exactly like any that he 

 had seen, but he thought they bore a general resem- 

 blance to pebbles found throughout the range of 

 geological strata wherever there is a bed of sand- 

 stone capped by clay. Professor Claypole claimed 

 to have seen similar specimens in Pennsylvania 

 deposits. 



The ' earthquake ' at New Madrid, Mo., in 1811, 

 probably not an earthquake. 



BY JAMES MACFAELANE OF TOWANDA, PENN. 



After dwelling upon the fact, that the locality of 

 the alleged earthquake was not the seat of any ap- 

 parent volcanic action, the author proceeded to state 

 his view that the event in question was due to a 

 different cause. He claimed that the locality was 

 underlaid by cavernous limestones of the St. Louis 

 group. He believed that what took place was a sub- 

 sidence, due to the solution of underlying strata. He 

 alluded to the descriptions afforded by Humboldt and 

 Lyell, the latter having visited the locality, and given 

 it acareful examination. The inhabitants described 

 it as a convulsion, taking place at intervals during 

 several months, creating new lakes and islands, 

 changing the face of the country. The graveyard 

 was precipitated into the Mississippi river ; forest- 

 trees were tilted in all directions; vast volumes of 

 sand and water were discharged on high. 



The author claimed that the long continuance of 

 such phenomena, which lasted for several months, 

 was an evidence that they proceeded from mere sub- 

 sidence, and not from earthquake shock. In respect 

 to the geology of the region, he stated that New 

 Madrid and its vicinity rested on tertiary or quater- 

 nary strata. Underlying sub-carboniferous formations 

 are represented near the borders of the depression. 

 The sinking of a shaft brought to light coal, or coal- 

 shales; also there were coaly shales found in the 

 crevices and sink-holes thirty-five years after the so- 

 called earthquake. 



This paper elicited strong expressions of dissent 

 from several members. Professor Cox declared that 

 there were no sub-carboniferous rocks in that locality, 

 no caverns, no soluble limestones underlying the 

 surface. The shocks were sudden. There was great 

 destruction of life. No mere subsidence can account 

 for what actually happened. A question as to the 

 truthfulness of the reports from that region brought 

 out very contradictory opinions in the discussion-. 



Professor Cox, who had personally examined the 

 scene of the occurrences, declared that lie had found 

 evidences of great disturbance. Professor Nipher 

 suggested that the position of the trees, whether 

 upright or not, which were alleged to be at the bot- 

 tom of Reelfoot Lake (a lake formed at the time of 

 the earthquake), would help to determine whether a 

 subsidence, or an earthquake, had taken place. Some 

 doubt was expressed as to whether any submerged 

 trees were there. To these doubts and queries. Pro- 

 fessor Cox was able to give a definite answer: he 

 had seen the trees still upright beneath the water. 



Comparative strength of Minnesota and New- 

 England granites. 



BY N. H. WINCHELL OF MINNEAPOLIS, MINN. 



Having had recent occasion to test the qualities 

 of the building-stones of Minnesota, the author sub- 

 jected them to the usual tests of crushing, using for 

 this purpose specimens of two-inch cube. The spe- 

 cimens included sandstones, limestones, granites, and 

 trap-rocks, and numbered about 100. Great care was 

 taken in preparing them accurately. They were sent 

 to Gen. Gillmore at Staten Island, and there sub- 

 jected to the tests, which were applied by crushing 

 the samples, one in the direction of the schistose 

 structure and one across it. The following were the 

 results with twenty samples of Minnesota granites: 



Kind of stone. 



Dark tr.ap-rock, 

 rauBsive rae- 

 laphyr . . . 



Dark trap-rock, 

 from a dyke . 



Grray gabbro, 



massive, finei 

 Red, fine sien- 



ite . . . . 

 Red quartzose 



sienile . . . 

 Red quartzose 



Bienite . . . 



Red quartzite . 



Massive gray 

 quartzose si- 

 enitc . . . 



Fine - grained 

 gray sienite . 



Fine - grained 

 gray sienite," 



[ Taylor's Falls, ) 



Chisago coun- [ 



I ty ) 



[ Fischer's creek, 1 



n'rDuluth.St. [ 

 ' Louis connty, ) 

 [ Rice's Point, ) 



Duluth, St. [ 

 ' Louis county, ) 

 j Beaver Bay, | 

 I Lake county,] 

 i Watab, Benton I 

 I county . . .\ 

 [ East St. Cloud. ) 



Sherburne} 



[ county . . 

 ' Sauk Rapids 



Average of twenty samples. 



On bed . 

 On edge, 



On bed . 

 On eds:e, 

 On bed . 

 On edge, 

 On bed . 

 On edge, 



On bed . 

 On edge, 



On bed . 

 On edge, 

 On bed . 

 On edge. 



Strength in 

 pounds. 



106,000 

 103,000 

 103,000 

 103,000' 



Per 



cubic 

 inch. 



25,000 

 25,750 

 25,750 

 25,750 



Allowing for eleven per cent difference between 

 processes of crushing between steel-plates and be- 

 tween wooden cushions, this gives an average for 

 Minnesota granites of 23,318 pounds. 



> Estimated. 2 Probably imperfect sample. 



