300 



SCIENCE. 



[N. S. Vol. XVII. No. 425. 



rocks; the collecting of fossils, rocks and 

 minerals; the preparation of pamphlets 

 and descriptive catalogues showing the 

 mineral wealth of Canada ; displays of eco- 

 nomic minerals, etc., at international ex- 

 hibitions; contributions to archeology and 

 ethnology ; extensive correspondence of the 

 department, great variety of subjects treat- 

 ed of; information and encouragement 

 given to prospectors and explorers ; useful- 

 ness of the department as a means of in- 

 troducing producers and consumers to each 

 other, and in giving information and ad- 

 vice leading to the establishment of new 

 industries. 



Direction of Flow of the Ancient Beaver 



River Shown by Pot-holes: Richard R. 



HiCE, Beaver, Pa. (Introduced by H. 



L. Fairchild.) 



Evidence of the slope of abandoned 

 fluvial plains is not always conclusive as 

 regards the direction of flow of eroding 

 stream. Evidence of pot-hole formation 

 is conclusive. The abandoned fluvial plain 

 of Beaver River near Rock Point and 

 present stream's bed below Fallston dam 

 in same sandstone were cited. Views were 

 exhibited showing the diilerence between 

 the up-stream side and down-stream side of 

 pot-holes at Fallston dam, the down-stream 

 side being eroded and rounded off, the 

 up-stream side steep, perhaps undercut. 

 View of pot-hole on abandoned fluvial plain 

 near Rock Point, the steep side to the south, 

 the rounded and eroded side to the north, 

 thus showing that the forming stream 

 flowed northward. Pot-holes are only found 

 where stream is rapid, hence the ones on 

 abandoned fluvial plain indicate that the 

 eroding stream had considerable fall to the 

 northward, and thus the uniisual width of 

 the 'inner' valley or gorge, north of Wam- 

 pum, is partly due to the erosion of the old 

 north-flowing stream. 



The Origin of Ocean Basins on the Plane- 



tessimal Hypothesis : T. C. Chamberlin, 



Chicago, lU. 



The Planetessimal Hypothesis of the 

 origin of the solar system differs funda- 

 mentally from the Laplacian and other 

 gaseous hypotheses, and from the meteor- 

 oidal hypothesis as set forth by Lockyer 

 and Darwin. These latter assign the exten- 

 sion of the parent nebula to the opposed 

 movements, collisions and rebounds of the 

 constituent molecules or meteoroids. The 

 former assigns it to concurrent orbital 

 movement. In the gaseous and meteoroidal 

 hypotheses (as usually understood) the 

 aggregation is the simple work of gravity 

 following a reduction of the oscillatory 

 and colliding action. In the planetessimal 

 hypothesis the aggregation is dependent on 

 orbital conjunction. In the former the 

 aggregation is massive and relatively rapid ; 

 in the latter the aggregation is individual 

 and relatively slow. In the gaseous hy- 

 pothesis the temperatures are necessarily 

 very high, and the planets are formed by 

 detachments. In the meteoroidal concep- 

 tion of George Darwin, the conditions are 

 practically the same, and in that of Lockyer 

 they differ rather in degree and in detail 

 than in essence. In the planetessimal con- 

 ception the planets grew up separately 

 by innumerable accretions of infinitesimal 

 planetoids (planetessimals) and the ex- 

 ternal temperatures were not necessarily 

 high, since the orbits of the planetessimals 

 were normally direct and concurrent and 

 the aggregation came about by overtakes in 

 contradistinction to opposed collisions, and 

 the frequency of these was limited by the 

 concurrent direction of orbital movement. 



The purpose of the paper is to outline 

 the hypothetical origin of the ocean basins 

 under the planetessimal theory, to set forth 

 the simple self-selecting process by which 

 they were perpetuated and deepened, and 



