58 PROCEEDINGS OP THE WASHINGTON MEETING 



The Greuville sediments, which are thoroughly crystallized, were certainly 

 reorganized into new minerals under deep-seated conditions ; but, since the 

 strata were never highly compressed, it is evident that they were subjected to 

 essentially static rather than dynamic metamorphism. This explains not only 

 the retention of stratification surfaces to the present time, but also the in- 

 variable parallelism of stratification and foliation. 



Regarding the foliation of the syenite-granite series, it is believed that 

 during the process of intrusion the magmas were under only moderate lateral 

 pressure, if any ; that the process of intrusion was long continued ; that the 

 foliation was developed essentially as a flow-structure, under moderate pressure, 

 during the intrusion, and that the almost universal but varied granulation of 

 these rocks was produced mostly by movements in the partially solidified 

 magma, and possibly in part by moderate pressure applied after complete con- 

 solidation. 



The usual parallelism of both Grenville masses and foliation with adjacent 

 masses and foliation of the syenite-granite intrusives are readily accounted 

 for because the Grenville masses were swung into general parallelism with the 

 slow-moving magmatic currents. 



Presented in abstract extemporaneously. 



Discussion 



Prof. J. E. Wolff : In the Archean highlands of New Jersey, with a nearly 

 constant northeast striking and easterly dipping foliation and frequent north- 

 east pitching linear structure, it seems necessary to siippose strong lateral 

 compression. 



Further remarks were made by Professors R. A. Daly, M. B. Baker, 

 and George H. Chadwick, with reply by the author. 



Professor Coleman remarked : It seems to me that both sides in this inter- 

 esting discussion are entirely right, but in different areas. From my own field 

 experience at one point or another I can corroborate the statements made by 

 all who have joined in the discussion. There is no real contradiction between 

 them, since what took place in one region differed from what took place in 

 another. - 



LANDSLIDES IN UNCONSOLIDATED SEDIMENTS 

 BY DAVID H. NEWLAND 



(Abstract) 



The paper discusses landslides as an agency of degradation in regions of 

 low relief and loose sediments like the larger stream valleys in the glaciated 

 district. Occurrences in the terraced Pleistocene clay and sand beds of the 

 Hudson-Champlain Valley are referred to in particular, on account of the 

 number of available observations which extend over a considerable period of 

 time. 



Gravity disturbances in bedded clays and sands often occur on small 

 gradients. The materials as a whole possess less stability under varying con- 

 ditions of moisture content and climate than the unsorted heterogeneous ac- 



