February 9, i804. 
eight lifted from the quarry are sometimes made up mostly 
of this form. In division C are several forms; a hotice- 
able one has its fresh surface covered with mastoidal 
eminences; these when cut down by weathering leave a 
series of beautiful rings or concentric circles. 
of this species are not unlike an inverted saucer in shape. 
The species iound in A may be collected at. Chazy, 
N. Y., arid at many localities in Vermont; those in B and 
C at their appropriate horizons at Isle La Motte, Vt. The 
form in B is incidentally largely distributed through the 
country and will be found when looked for in the tiled 
floors of almost every public building where Isle La Motte 
marble has been used: In museums, too, it will be found 
under title of ‘‘ Isle la Motte banded limestone.”~ The 
place above all others for display of .S. vagosum is a little 
island, at the entrance of Button Bay, three miles south 
of Fort Cassin, Vt., where a layer 20 to 30 inches thick is 
exclusively of this form and Colwmnazvia alveolata, H. 
The following facts are evident: (1) the genus Stroma- 
tocerium does not make its first appearance in the Black 
River; it is there rather in its decadence; (2) it appears 
inthe lower Chazy, following close upon the Cryptozoon, 
~ and persists through the different divisions; (3) it cannot 
of itself be trusted as a safe indication of the Black 
River. 
However, it should be noticed that Stromatocerium 
vagosum iS most frequently paired with Columnaria 
alveolata, and the presence of the two forms establishes 
beyond question the presence of the Black River. 
DR. CALLAWAY AND THE PRODUCTION OF 
CRYSTALLINE SCHISTS BY DYNAMO- 
METAMORPHISM. 
EY fo Vivo IRISID WINNS IDI (CaS IANS MADINA ING Ne 
Axsout fifteen years ago, while setting a piece of heavy 
mining machinery that revolved on a vertical shaft, work 
was brought to a stand by the discovery that the journal, 
intended as a chair and box for the cone-shaped bearing, 
was considerably too small. A speculative workman 
thought it might wear downto shape, however, and started 
the machinery. The experiment, though of doubtful 
success from a mechanical standpoint, was _ brilliantly 
successful in another light. The bearing and journal, 
both of drop-forged steel, were welded to each other and 
broke into a dozen pieces. ‘The interesting point, how- 
ever, was the fact that two forgings of laminated steel 
under the agency of heat were converted to a metamor- 
phicform. At the surface of welding the laminated steel 
became crystalline, and even the parts at some distance 
became semi-crystalline. It was a fair illustration of 
what is now called dynamo-metamorphism. 
In a very remarkable paper presented to the Quarterly 
Journal of the Geological Society of England, Mr. Charles 
Callaway, D. Sc., F.G.S., has published the result of his 
researches on the origin and formation of certain crystaline 
schists found in the Malvern Hills, inthe west of England. 
A close study of these schists during a period of five 
years has brought Dr. Callaway to the conclusion that 
they were produced by a dynamo-metamorphosis not 
different in essential principles from the illustration de- 
scribed inthe preceding paragraph. Ordinarily, meta- 
morphism in rocks may be briefly described as the change 
that a sedimentary rock undergoes when subjected to in- 
tense pressure inthe presence of heat and moisture. The 
rock becomes more or less crystalline, and there is a 
tendency from homogeneity to heterogeneity in mineral 
structure. The production of metamorphism by the 
Examples 
SCIENCE #6 
shearing 6f rock and the gradual sliding or movement of 
the one tiiass upon the surface of the other is called 
dynamo-metamorphism. Neither the name nor the idea 
originated with Dr. Callaway, but the thorough exposition 
the subject has received at his hands entitles him to a 
foremost place among the pioneers in this field of research, 
and the results he has obtained are an important step in 
advance in the field of dynamic geology, 
The Malvern Hills are mainly composed of masses of 
igneous rock, granitic in etharacter, the constituents 
chiefly considered being binary granite and two kinds of 
dorite. Incertain localities there are exposed bands of 
crystalline schist, apparently as seams of subsequent in- 
tercalation but really cataclasticin origin. These seams. 
are the shear-zones within which the schist-making pro- 
cess occurred. Aside from the normal metamorphism 
which took place, the chief factor seemed to be a distinct 
shearing movement that resulted in a fusion sufficiently 
complete to produce plasticity. 
Among the mechanical changes was the transformatiom 
of diorite into mica-gneiss. In the process of transfor 
mation the pulverized mineral not infrequently passed 
through an intermediate stage of laminated grit that simu- 
lated a sediment. A still more interesting change was 
the injection of potash and potassium feldspar into diorite, 
and a similar transference of the corresponding sodium 
salts into granite. In still other cases, diorite and 
granite were mutually interlaced. Chlorite and ferric 
oxide produced by the decomposition of diorite were 
injected or infiltrated into the cracks, cleavage and shear- 
planes of crushed granite and often migrated to a con- 
siderable distance, giving rise to an interfoliation of 
chlorite and biotite with the quartz, feldspar, and musco- 
vite of the resulting gneiss. 
The mineral changes may be classified as (a) decomposi- 
tion, (4) transition, and (c) reconstruction. ‘lhe massive 
rocks pass into schists througha process of decomposition, 
followed and partly accompanied by a process of recon- 
struction, in which the newly-formed quartz and feldspar 
crystallize, after the secondary consolidation. ‘The chief 
mineral changes of the schist-making process are (a) the 
replacement of orthoclase by quartz and muscovite; (0) 
of plagioclase by the quartz and muscovite; (c) of chlorite 
by biotite and white mica; (@) and of biotite by white. 
mica. The liberation of potassium from the granite is 
sometimes accompanied by silicification of the veins and 
the production of garnets. The reconstruction of feldspar 
is also a prominent feature in the metamorphism. 
Among the chemical changes the following are note- 
worthy : (a) the mutual transference of sodium and 
potassium compounds between diorite and _ granite, 
also previously noted among physical changes; (4) 
the removal of sodium, potassium, magnesium, cal- 
cium, aluminium and iron compounds when diorite is con- 
verted to gneissoid quartzite; (c) the retention of alu- 
minium and the elimination of alkaline compounds when 
diorite is metamorphosed to muscovite. 
Dr. Callaway’s researches involved the preparation of 
about 500 thin sections of rock for study with the micro- 
scope, and a large number of chemical analyses. His 
hypotheses are bold and ingenious, involving metasoma- 
tosis onalargescale. Subsequent investigations, however, 
have not disproved them; on the contrary they have been 
strongly confirmed. It is interesting, moreover, to com- 
pare the work of Dr. Callaway with that of Mr. Van 
Hise on the schists of the Penokee iron-bearing series 
(U. S. Geol. Survey, Rep. 1888 and 1889, pp. 429 et seq.). 
The ideas shadowed in Mr. Van Hise’s report could not 
have been more fully confirmed than they have been by 
Dr. Callaway, working independently at the same time on 
rocks several thousand miles away. 
