53° 



NA TURE 



{Sept. 25, 1884 



On Fluxion-Structure in Till, by Hugh Miller, A.R.S.M., 

 F.G.S., Geological Survey of England and Wales. — It lias long 

 been recognised as one of the characteristics of the till that its 

 long-shaped boulders are striated lengthwise. They have, as it 

 las been concisely expressed, been "launched forward end on." 

 From the minute and magnifiable striie upon the smaller {e.g. 

 almond-sized) boulders it also appears that these at least have 

 1 een carried forward, involved in the matrix, and wen 

 chiefly by its particles. Under the microscope these particles 

 exhibit most of the varieties of form and glaciation that are 

 found among larger boulders. The structure of the till in open 

 situations shows that the axes of its stones have been turned by 

 a common force in the direction of glaciation ; it exhibits a 

 rough structure comparable to the fluxion-structure of igneous 

 rocks, the smaller boulders dividing around and apparently drift- 

 ing past the larger, like the tide round an anchored skiff. These 

 structures, which have been found by the author over many 

 hundreds of square miles, chiefly in the north of England, indi- 

 cate that at least a surface-layer of the till was dragged along, 

 with a shearing movement of particle upon particle, producing 

 intimate glaciation within its mass. Proofs are adduced that 

 this moving layer was in general a surface-layer only, and that 

 the till did not, as has often been supposed, move forward en 

 masse, licking up its additions from beneath. This is the only- 

 intelligible explanation of the order (as well as the structure) of 

 the boulder-clays of which the author has any practical know- 

 ledge. In up-lying situations, where the drift consists of raw 

 material, fluxion-structures are seldom detected. In sheltered 

 spots they are not generally developed. They are characteristic 

 of well-kneaded till in open situations, liable, however, to ob- 

 scuration by contortions within the mass. Of twelve experi- 

 mental attempts made near the watershed of England in East 

 Cumberland, 600-900 feet above the sea, to determine the iee- 

 movement from this structure alone, eight were correct, three 

 indeterminate, and only one misleading. The pressure and 

 movement capable of producing this widespread fluxion-structure 

 seem to have been that of some mass vast and far-spreading — 

 closely investing, slow-moving, and heavily dragging — such as 

 glacier ice. It needs only to be assumed that the confluent 

 glaciers communicated something of their own movement and 

 structure to the ground-moraine below. 



On the Southward Ending of a Great Synclinal in the Taconie 

 Range, by James D. Dana, LL.D. — The Taconie Range, which 

 gave the term "Taconie" to geology, lies in Western New 

 England, between Middlebury, in Vermont, on the north, and 

 Salisbury, in Connecticut, on the south. In former papers, 

 published in the American Journal of Science, the author has 

 shown, first, that the rocks constituting the range vary as we go 

 from north to south, from roofing-slate and hydromica (orsericite) 

 schist to true chloritic and garnetiferous mica schists ; secondly, 

 that these schists lie mostly in a synclinal or compound syn- 

 clinal ; thirdly, that the crystalline limestone along the eastern 

 foot is one with that along the western, the limestone passing 

 under the schist as a lower member of the synclinal ; and 

 fourthly, that since the limestone contains in Vermont (according 

 to the discoveries of the Vermont Geological Survey, and also 

 of Mr. A. Wing), and in the State of New York, fossils of the 

 Lower Silurian, ranging from the inferior divisions to the higher, 

 the Taconie schists are probably of the age of the Hudson Kiver 

 group or Llandeilo flags. The author's papers further show 

 that while a large part of the Taconie Range has eastward dip 

 on both the east and west sides, a southern portion about twelve 

 miles long, consisting of Mount Washington in south-western 

 Massachusetts and its continuation into Salisbury, Connecticut, 

 is a broad tray-shaped synclinal, the dips of the two sides being 

 toward one another, like the sides of an ordinary trough. The 

 width of the broad synclinal between the limestone belt on either 

 side is about five miles. As the result of investigation during 

 the last two years, the synclinal character of this Mount Wash- 

 ington part of the Taconie Range is illustrated in the paper by 

 new sections, and by facts connected with the dying out of the 

 great synclinal (or compound synclinal) in the town of Salisbury. 

 The mean height of Mount Washington above the sea-level is 

 about 2000 feet, and above the wide limestone region on either 

 side and to the south, about 1250 feet. The synclinal virtually 

 ends along an east and west line through the village of Lake- 

 ville, in the town of Salisbury, where a beautiful lake lies within 

 the limestone area. The surface of the mountain region descends 

 1000 feet in the southern, or last, three miles ; and in the 

 latitude of Lakeville, the width, as the map presented shows, 



diminishes abruptly from five miles to a narow neck of six-tenths 

 of a mile. The area south is of limestone, and the neck of 

 schists referred to is hardly 150 feet in height above it. The 

 limestone may in some places be seen emerging from beneath 

 the schist at a small angle ; and at one locality a low oven- 

 shaped anticlinal of limestone has the schist covering all but 

 a narrow portion at top ; the quarrymen had to remove the 

 schist to work at the limestone. Several narrow strips or belts 

 of limestone, S. 15 W. in direction, corresponding with the 

 direction of this part of the range, show out through the sides of 

 the mountain where local anticlinals have had their tops worn 

 off. Further, the dip of the schist over much of the southern 

 slope is southerly and at a small angle, but with many local 

 anticlinals and synclinals. In addition, there are small areas of 

 schist in the limestone region, like straggling portions of the 

 dwindled mountain, which appear in general to be remains of 

 local flexures. There is the plainest evidence that the 

 limestone formation of southern and south-eastern Salisbury 

 comes out from beneath the dwindled, ffattened-out. and worn- 

 off mountain synclinal. And the reason why this limestone is 

 exposed to view over plains miles in width, east and west of the 

 Taconie Mountain, as well as to the south, is simply this, that 

 the once overlying schist has been removed because in badly 

 broken anticlinals and synclinals. The paper closes with an 

 allusion to the orographic, stratigraphical, and lithological 

 interesl of the facts, and to their important bearing on the ques- 

 tion of the origin and chronology of certain kinds of crystalline 

 locks, such as chloritic, garnetiferous, and staurolitic mica 

 schists, as well as others less coarsely crystalline. 



The Primitive Conocoryphean, by G. F. Matthew, A.M., 

 F.R.S.C. — Relates to the development of the species Cteno- 

 cephalus matthewi and other Conocorypheans of the Acadian 

 fauna, and is considered under the three heads, viz., the Develop- 

 ment of the Glabella ; the Acquisition of Sensory Organs; and 

 the Decoration of the Test. Under the first head it is shown 

 that the peculiar glabella of the species above referred to is 

 closely related to the early history of the trilobite. The glabella, 

 in its earliest stage, is very different from that of the adult, and 

 in outline is not unlike that of Paradoxides ; it also resembles 

 this species in the position of the ocular fillet. At the next stage 

 the glabella or axial lobe becomes trumpet-shaped, as in 

 Carausia, and in the third the glabella proper is developed by 

 the segmentation of the axial lobe : the glabella and ocular 

 fillets now resemble those of Ptychopar a. In the following 

 stages the family characters of the Conocorypheans begin to 

 assert themselves, especially the widening of the base of the 

 glabella, the appearance of the canals connected with the ocular 

 ridges, and the development of spines. (2) The Acquirement 

 of Organs of Sense. — The ocular fillet appears, in tre second 

 stage of growth, as a faint, narrow ridge, close r to the anterior 

 marginal fold, and extending but a short distance from the 

 glabella. It is not until the fifth stage of growth that the rami- 

 fying branches which spread from the ocular ridge to the anterior 

 margin made their appearance. The ocular lobe and sensory 

 apparatus connected with it are more distinctly visible on the 

 under than on the outer surface of the test, and the canalets con- 

 nected with the lobe spread over the anterior slopes of the 

 shield, and extend to the anterior margin. In the tuberculated 

 species they connect by hollow spines with the outer surface. In 

 one species they cover a wider space than in the others, extend- 

 ing some distance behind the ocular ridges and over the front of 

 the glabella. (3) Decoration of the Test. — In all the Acadian 

 species of this group but one, the surface of the test at maturity 

 is covered with tubercles and spines similar to the surface- 

 markings of Conocoryphe sulgeri, &c. In the earliest stages, 

 however, no such tubercles are found, but the surfac 

 smooth or scabrous. In Ctenocephalus matthewi the surface, in 

 the first three stages of growth, appears smooth ; in the fourth, 

 tubercles begin to appear, and about the fifth stage all projecting 

 parts of the test are studded with them. Those on the glabella 

 and frontal lobe are arranged in transverse rows, those on the 

 cheeks in interrupted rows conforming more or less to the 

 periphery of these protuberances. Towards the adult stage 

 these tubercles and spines become more irregular in position and 

 number, conforming in this respect to the law of development in 

 the Ammonites, expounded by Prof. Alphonso Hyatt. 



The Value of Detailed Geological Maps in relation to Water- 

 Supply and other Practical Questions, by W. Whitaker, B.A., 

 F.G.S., Geological Survey of England. — Those maps of the 

 Geological Survey of England in which various divisions of the 



