Feb. 22, 1872] 



NATURE 



331 



hold the views which Prof. Hunt has attributed to them 

 in his address. We are glad to know that this is not the 

 usual American method of dealing with authorities. 



Gumbel and Credner are the other two claimed sup- 

 porters of his views. They have sustained Mr. Hunt's 

 opinions as regards the Eozoon and the origin of the 

 serpentine constituting it. But whether they disagree with 

 Haidinger and all others as to pseudomorphs of serpentine, 

 and of other hydrous silicates, I cannot say. 



9. That while setting down the Taconic rocks, and 

 rightly, as Lower Silurian in age, he denominates the 

 micaceous gneisses, diorites, epidotic and chloritic, 

 steatitic and serpentinous rocks, talcoid mica schists, 

 quartzites, and clay-slates (which are always without 

 staurolite or andalusite), in fact, the whole range of meta. 

 morphic rocks, with small exceptions, between the Con- 

 necticut river and the great limestone formation of the 

 Green Mountains (admitted to be Lower Silurian), as the 

 Green Mountain Series, and makes the whole " pre- 

 Cambriati " in age, although the region has not been 

 examined by any one stratigraphically with the care 

 necessary for a positive opinion ; and, although there are 

 gneisse?, mica schists, and chloritic talcoid (or mica) schists 

 in the Taconic series, and there'ore of admitted Lower 

 Silurian origin, which are closely like those of his Green 

 Mountain Series. 



10. That he denominates, in like manner, the gneisses, 

 mica schists (said to be richer in mica than those of the 

 Green Mountain Series), hornblendic gneisses and schists, 

 micaceous and clay-slates containing andalusite, cyanite, 

 or staurolite, and certain limestones, existing east of the 

 Connecticut river, as a IVhite Mountain Series, and makes 

 these a newer " pre- Cambrian " than the Green Mountain 

 Series : — when there is the same want of stratigraphical evi- 

 dence as to age as in the former ; and when Prof. C. H. 

 Hitchcock's discoveries of Helderberg corals (Lower 

 Devonian, according to Billings, or else upper beds of the 

 Upper Silurian), at Littleton, not far north of the western 

 extremity of the White iVIountain Series, makes it more 

 proba'ole that part of the White Mountain Series of beds 

 areof Helderberg age rather than pre-Silurian ; and his dis- 

 covery of labradorite rocks on the south-western margin 

 of the White Mountains, wholly unlike any of the so- 

 called White Mountain Series, shows further that a vast 

 amount of study in the field is needed before the dictum 

 of any one respecting the age of New Hampshire rocks 

 is worth much. 



It is now proved that there are labradorite rocks in 

 Waterville and Albany, N.H., on the borders of the 

 White Mountain region, which zre probabiy oi Laurentian 

 age ; that on the other side of the White Mountain line, 

 but 25 miles to the north-northwest, there are fossil-bear- 

 ing, metamorphic rocks of the Helderbero (upper or 

 lower) period ; that 100 miles south-southwest, in Ber- 

 nardston. Mass,, or central New England, there are other 

 fossil-bearing metamorphic Helderberg rocks, some of the 

 well-preserved crinoidal stems (as the writer has seen, as 

 well as read of in the account of Prof Hitchcock) an ineh 

 in diameter. Who then knows whether all, or any, of 

 the long intermediate periods of geological time, from 

 the Laurentian to the Devonian, are represented in the 

 New Hampshire metamorphic rocks lying between these 

 limits ? When observation has given positive knowledge, 

 we may then have several " White Mountain Series." 



II. That he has relied, for his chronological arrange- 

 ment of ihe crystalline rocks of New England and else- 

 where, larg' ly on litholo,;ical evidence, and commends 

 this style of evidence, when such evidence means nothing 

 until tested by thorough stratigraphical investigation. 

 This evidence means something, or probably so, with 

 respect to Laurentian rocks ; but it did not until the age 

 of the ro ks, in their relations to others, was first strati- 

 graphically asceitained. It may turn out to be worth 

 something as regards later rocks when the facts have 



been carefully tested by stratigraphy. A fossil is proved, 

 by careful observation, to be restricted to the rocks of a 

 certain period, before it is used — and then cautiously — for 

 identifying equivalent beds. Has anyone proved by 

 careful observation that crystals of staurolite, cyanite, or 

 andalusite, are restricted to rocks of a certain geological 

 period ? Assumptions and opinions, however strongly 

 emphasised, are not proofs. 



It is no objection to stratigraphical evidence that it is 

 difficult to obtain ; is very doubtful on account of the 

 difficulties ; may take scores of years in New England to 

 reach any safe conclusions. It must be obtained, what- 

 ever labour and care it costs, before the real order and 

 relations of the rocks c^.n be known. Until then, litho- 

 logy may give us guesses, but nothing more substantial. 



Mr. Hunt's arguments with reference to the White 

 Mountain Series, as urged by him in 1S70, will be found in 

 Sillintan'sjournal. ii. 1. 83. Both there, and in his address, 

 may be seen the kind of evidence with which he fortifies, 

 or supplements, that based on the character of the rocks. 

 Direct stratigraphical investigation over the region itself, 

 in which ad flexures, faults, and unconformabilities have 

 been thoroughly investigated, is not among the founda- 

 tions of opinion which he brings forward. 



He endeavours to set aside the objections to his views 

 suggested by the existence of Devonian or Helderberg 

 rocks in central and northern New England ; but he pre- 

 sents, for this purpose, only some general considerations 

 of little weight, instead of definite facts as to the extent 

 and variety of the metamorphic strata that are part of, 

 because comformable to, these Helderberg beds. Had 

 he studied up these stratigraphical relations with the 

 care requisite to obtain the truth, and all the truth, 

 perhaps he would no longer say— it is " contrary to my 

 notions of the geological history of the continent to sup- 

 pose that rocks of Devonian age could in that region 

 have assumed such lithological characters." Notions often 

 lead astray. James D. Dana 



NOTES 



The Royal Horticultural Society has taken a step which may 

 prove very advantageous to the interests of science, namely, the 

 appointment of a botanical Professor, who, by lectures, answers 

 to personal inquiries, and other means, shall assist in establishing 

 a more correct knowledge of the principles of botany and hord- 

 culture, and of the names of plants, among those of the Fellows 

 and their gardeners who are desirous to profit by the opportunity. 

 Among the dudes of the Pro'essor of Botany will be to conduct 

 the scientific business of the society, both horticultural and 

 botanical ; to enter into communication with horticultural and 

 botanical establishments at home and abroad ; to conduct the 

 meetings and edit the publications of the society; to give courses 

 of lectures on scientific botany to the gardeners and others ; and 

 to have a general superintendence of the gardens at Chiswick. 

 The appointment to this office of Mr. W. T. Thiselton-Dyer, 

 late Professor of Botany at the Royal College of Science, 

 Dublin, is a guarantee that the cultivation of scientific botany 

 will not be neglected. 



Dr. David Ferrier has been appointed Professor of 

 Forensic Medicine at King's College, London, vice W. A. Guy, 

 M. B., resigned. 



The Secretary of State for India has appointed Mr. A. G. Green- 

 hill, Fellow of St. John's College, Cambridge, Professor of 

 Applied Mathematics at the Civd Engineering College, Cooper's 

 HiU. Mr. Greenhill graduated as Second Wrangler in 1870, 

 and was bracketed equal with the Senior Wrangler for the Smith's 

 Prize ; he also gained a Whitworth Scholarship while an under- 

 graduate. 



