234 



SCIENCE. 



[N. S. Vol. XVU. No. 423 



DISCUSSION AND CORRESPONDENCE. 



THE USE OP THE WORD GEEST IN GEOLOGY. 



To THE Editor of Science: The American 

 Geologist for December, 1902, reprints an ex- 

 tract from the 11th Annual Report U. S. 

 Geological Survey, by W J McGee, upon the 

 use of the term geest in geology. Dr. MoGee 

 calls attention to the fact that there is no 

 general term in comnron use to designate the 

 undisturbed products of weathering, and pro- 

 poses the Dutch word geest, as used by De 

 Luc, Eaton and Beck, to distinguish such 

 material in situ from alluvium or tr^tnsported 

 material. Dr. McGee overlooks tne fact that 

 geesi and alluvium are themselves specific 

 terms denoting members of a class, while for 

 the class itself a common descriptive or 

 ' denotative ' term is still wanting. In his 

 first sentence he introduces his subject as 

 ' the superficial mantle of rock debris.' Later 

 it appears as ' the extensive mantle,' etc., and 

 ' the unconsolidated materials by which these 

 [solid] rocks are mantled.' Every recent 

 writer upon geology and physical geography 

 has had to wrestle with this problem and has 

 usually solved it by some circumlocution. 

 The older writers, Lyell, Dana, Prestwich, 

 Geikie, Le Conte and even Scott use only the 

 term soilj and appear to do so without any 

 sense of unfitness or inadequacy. Brigham 

 (' Text-book of Geology ') discusses ' the whole 

 sheet of crumbled rock material which man- 

 tles most of the rocky foundation of the 

 lands,' but finds no better term for it than 

 ' this mantle.' Elsewhere he uses ' rocky 

 debris ' and ' land waste.' Gilbert and Brig- 

 ham (' Introduction to Physical Geography ') 

 use several variations of the theme, ' earthy 

 mantle that covers the rock,' ' waste cover,' 

 ' earthy cover,' ' waste mantle.' They state 

 explicitly : ' The student should distinguish 

 clearly and use it [soil] only of the veneer 

 of earthy matter which is especially fitted to 

 support life.' Davis (' Physical Geography ') 

 commonly uses waste with various modifiers, 

 as ' rock waste,' ' land waste,' ' sheet of 

 loosened rock waste,' ' cloak of rock waste,' 

 ' waste sheet.' In the Journal of Geology, 

 Vol. 10, p. 98 fF., he uses many times the 

 phrases ' sheet of waste ' and ' cloak of waste.' 



Merrill ('Eocks, Rock Weathering and 

 Soils ') strikes out boldly and manufactures 

 a new term, regolith, blanket rock for the 

 ' entire mantle of unconsolidated material, 

 whatever its nature or origin.' Eor non- 

 classical students I have translated regolith 

 into mantle rock, and have used that term for 

 several years with perfect satisfaction. The 

 above quotations show how difficult it is to 

 avoid some term expressive of the idea of a 

 cover or mantle. Waste is open to the objec- 

 tion that it expresses a half truth in such a 

 way as to give a false impression. It is waste 

 only in relation to its past. In its destination 

 and future functions it is not waste, but ' the 

 dust of continents to be.' It is always a 

 mantle which covers some other kind of rock, 

 and in geography the distinction between the 

 mantle and that which it covers is more im- 

 portant than the distinctions between aque- 

 ous, igneous and metamorphic rocks. I sug- 

 gest, then, the term mantle rock for the 

 material which Merrill has named the rego- 

 lith, and hope that it may find favor and 

 supply a long-felt want. It is plain Saxon, 

 expresses the most distinctive and striking 

 character of the material, has no misleading 

 implications and fits readily into any place 

 where it is needed. I find in the note-books 

 of my students such records as these: "Law- 

 rence Co., bed-rock limestone, mantle red clay. 

 Green Co., bed-rock shale, mantle glacial 

 drift." To substitute waste, detritus, debris, 

 geest, alluvium, unconsolidated materials, or 

 any other term for mantle in these phrases 

 would be distinctly no improvement. 



Charles E. Dryer. 

 Teeee Haute, Ind. 



atavic mutation. 

 To THE Editor op Science: Dr. White's 

 article on aggregative atavic mutation of 

 the tomato, in Science for January 9 recalls 

 to me a case of — apparently — similar atavic 

 mutation, which Dr. White should be in a 

 position to investigate, if, indeed, he has not 

 already done so. When I lived in Washing- 

 ton, some ten years ago, we were rarely able 

 to get any really siveei sweet corn, such as is 

 so abundant here in New England. The 



