614 



SCIENCE. 



[N. S. Vol. XI. No. 277. 



of the eggs. Contrary to the common 

 prejudice, it is a fact that spermatozoa are 

 much more sensitive and are killed much 

 sooner than the egg. 



My experiments at Pacific Grove were 

 carried ^on with Strongylocenti-otus francis- 

 camis and purpuratus. In both animals 

 artiiicial parthenogenesis can easily be ac- 

 complished. 



In the experiments at Pacific Grove I 

 enjoyed the valuable assistance of Mr. W. 

 E. Garrey. Jacques Loeb. 



The TJniveksitt or Chicago. 

 April 3, 1900. 



A CURIOUS PHASE OF INTEE-STREAM ERO- 

 SION IN SOUTEEEN OREGON. 

 The 'Kogue Eiver Valley,' in southwest- 

 ern Oregon, is one of the five great de- 

 pressed areas of the Pacific Coast country, 

 which separate the Klamath and Coast 

 ranges from the Sierra Nevada and Cascade 

 Mountain systems. Its main stream, the 

 Eogue Eiver, issues from deep caiions in 

 the Cascade Range, and flows thence, in its 

 middle course, through a broad valley 

 whose floor is a flat plain, two to five or 

 more miles in width. In crossing the 

 basin, the stream found soft strata to work 

 upon, and not being obliged to cut deep, it 

 eroded a broad valley, strongly contrasting 

 with the caiions above and the narrow, 

 rocky gorge in which the river makes its 

 passage through the Klamath Mountains 

 near the sea. All the tributary streams 

 within the area of the basin have eroded 

 similarly bi'oad, flat-bottomed valleys, and 

 between them they have reduced to a local 

 base-level, the greater portion of an area 

 forty or fifty miles in length by twenty to 

 thirty miles in width. Within these limits 

 there are many hills and low mountains, 

 remnants of the Tertiary strata in which 

 the broad valleys are excavated, but they 

 are quite insignificant in comparison with 

 the high mountains which enclose the basin, 



of which the Siskiyou range on the south- 

 west rises to 7000 feet and over, and the 

 Cascades on the east to 6000 feet on the 

 average, surmounted by the beautiful vol- 

 canic, snow-clad cone of Mt. Pitt. 



Since the partial base -leveling of the 

 ' Rogue River Valley,' which doubtless 

 was accomplished nearly at sea-level, the 

 territory has been elevated and the basin 

 tilted, mainly toward the northwest. The 

 valley plain descends from an altitude of 

 about 1900 feet at Ashland to less than 

 1300 feet where the C. & 0. R. R. ap- 

 proaches the Rogue River. In ascending 

 along the river, the gradual rise in the 

 plain is everywhere quite perceptible, and 

 it has attained an altitude of approximately 

 2000 feet where the main stream issues 

 from the foot-hills proper of the Cascade 

 Mountains. This tilting has increased the 

 gradient of the streams, causing them to 

 cut below the old level, and all the prin- 

 cipal ones now flow in comparatively nar- 

 row, sharp-cut, canon-shaped troughs, ex- 

 cavated from 30 to 75 feet below the valley 

 plain. These canons are few and widely 

 separated, telling of the youthfulness of 

 this new cycle of erosion. 



The inter-stream tracts are broad plains, 

 undissected by deep guUeys. Some por- 

 tions of them are without timber or even 

 chaparral, although generally supplied with 

 a sparse growth of grass, and in the ver- 

 nacular of the country are known as 

 deserts. It is on these ' deserts,' some of 

 which are four or five miles in length and 

 one to three miles in width, that is de- 

 veloped the peculiar type of surface erosion 

 which has given rise to this paper. 



"When viewed from a distance, the sur- 

 face of the ' deserts ' appears to be remark- 

 ably even, suggesting an absolutely un- 

 eroded, water-laid deposit such as might 

 result from the complete filling of a broad, 

 shallow lake basin. But, upon endeavoring 

 to cross these barren plains in the rainy 



