May 17, 1918] 



SCIENCE 



493 



Conditions of deposition of marine salts and their 



bearing on the potash problem: A. W. Grabau. 



The three theories which have been developed to 



explain the widespread occurrence of salt deposits 



in the past are: (1) The bar theory of Ochsenius. 



(2) The cut-off theory and, (3) the desert salt 

 theory of Walther. (1) According to the first a 

 constant supply of sea water is derived from the 

 neighboring sea or large salt-water body. It is 

 illustrated by the Karabugas Gulf. Such deposits 

 are characterized by basal gypsum beds, an abun- 

 dance of organic remains in the intercalated mud 

 layers and by normal marine deposits of the same 

 age in the neighboring sea from which the salt 

 water was supplied. Mother liquor salts can only 

 be developed as the result of a final cutting off of 

 the basin and complete evaporation. (2) Salts de- 

 posited in a basin filled with normal sea water and 

 cut-off from the sea, wiU be characterized by a 

 basal gypsum or anhydrite layer, by an absence of 

 organic remains except at the base, by the con- 

 centration of the salts into the deeper lying por- 

 tion of the basin and by a regularity of the re- 

 sulting series of salts. Such salt deposits may 

 be enriched by additions from connate sources, 

 with the result that the sodium chloride will be in 

 excess of the other salts. Mother liquor salts are 

 normally deposited in such a drying basin. The 

 Stassfurt salts are believed to have had this origin. 



(3) Marine salts enclosed as connate sea water and 

 salts, may be concentrated in desert basins far 

 from the sea. They are characterized in general 

 by the absence of a basal gypsum or anhydrite 

 bed, though these salts may occur sporadically. 

 Irregularity of deposition, lens-like character of 

 the individual beds, and an absence of marine or- 

 ganic remains are among the other criteria of 

 such a deposit. Moreover contemporary marine 

 deposits are not necessarily formed in the immedi- 

 ate neighborhood of the salt basins. Mother liquor 

 salts are generally and perhaps normally absent 

 from such deposits, this applying especially to the 

 potash salts which will be adsorbed by the soil 

 through which the drainage waters pass before 

 reaching the evaporation basin, while those that do 

 reach this basin are apt to be dissipated as shown 

 by Walther. The Salina salts of North America 

 are believed to have had such an origin. 



The Ordovician terranes of central Vermont: 



Charles H. Richardson. 



The author tersely gives the early geological ■ 

 history of central Vermont, from Algonkian time 

 to the close of the Ordovician. He describes the 

 Cambrian sedimentaries that flank the Ordo%-ician 



on the west and form the eastern foot hills of the 

 Green Mountains. The paper describes the Iras- 

 burg conglomerate which marks the base of the 

 Ordovician terranes in central Vermont and the line 

 of an erosional unconformity between the Cam- 

 brian and the Ordovician already followed for 

 more than 100 miles in Canada and Vermont. It 

 shows that the boulders in the conglomerate are 

 all pre-Ordovician and the matrix Ordovician. 

 The author then gives the general distribution of 

 the three belts, non-continuous, of the Memphrema- 

 gog slates, their composition and economic possi- 

 bilities. This is followed by a description of the 

 three belts of the Waits River limestone which 

 are continuous and have been followed southward 

 from the international boundary for 100 miles. 

 These formations include the numerous beds of 

 Waits River and Washington marbles which are 

 catalogued as marble reserves. A short discus- 

 sion is included of the intrusives in both the Cam- 

 brian and Ordovician terranes with a citation of 

 about 20 different types of igneous rocks that 

 have already been identified in these formations. 

 The author lays stress upon the paleontology of 

 the area because central and eastern Vermont 

 were regarded as devoid of all fossil content prior 

 to his discovery of numerous beds of graptolites in 

 both the Memphremagog slates and the Waits 

 River limestones. These graptolites have already 

 been discovered in every township south of the in- 

 terna.tional boundary near the central north and 

 south line in the state for a distance of approxi- 

 mately 100 miles. They are present in each of 

 the three phases of the Memphremagog slates and 

 in each of the three phases of the Waits River 

 limestone. Their presence proves sedimentation 

 began in central Vermont in early Ordovician time 

 (Beekmantown) and closed with the lower Trenton. 

 The graptolites have been identified by Dr. Rudolf 

 Ruedemann, State Paleontologist, Albany, N. Y. 



Postglacial contineiital uplift: Herman L. Fair- 

 child. 

 The influence of the Ontario dome on the develop- 

 ment of the Tertiary drainage of western New 

 Tork, Ontario and Michigan: Amadeus W. 

 Grabau. 



The author has previously outlined the series of 

 domes and basins which had their maximum de- 

 velopment in eastern North America during the 

 Appalachian revolution, but which had initial de- 

 velopments preceding that. The Paleozoic strata 

 from which the cuesta topography of New York 

 and Ontario was carved were not coastal plain 

 strata to the Canadian shield as often assumed, 



