\2'2 Tin American Geologist February, 1894 
Post-Glacial eolian net ion in southern New England. By J. B. 
Woodworth. (Amer. Jour. Sci., 3, vol. 47, pp. 63-71, Jan., 1894.) 
Pebbles having facettes cut by wind-blown sand are described, and 
several localities are mentioned where these pebbles occur. From the 
fact that this carving of pebbles is essentially a subaerial phenomenon, 
the presence of such pebbles in any formation is proof of an elevation 
above sea level. The term "glyptolith" {cilyptos, carved; lithos, stone) 
is suggested for a rock surface carved by wind-blown sand. 
The structures, origin ami nomenclature of the acid volcanic rocks 
of South Mountain. By F. Bascom. (Journal of Geology, vol. i, No. 
8, pp. 813-832, Nov.-Dec, 1893.) 
Three types of rocks are represented in this area: (1) A Lower 
Cambrian conglomerate and sandstone, and below these (2) brilliantly 
colored, acid, volcanic rocks, and (3) dark green, basic, volcanic rocks. 
The author expects soon to present the results of a detailed investiga- 
tion of these different types, but in this paper only some features of the 
acid volcanics are discussed. The object is to show that these rocks 
were originally identical with their recent volcanic analogues, that their 
present differences are due to changes subsequent to solidification 
(chief among which is devitrification), and to propose a name which 
shall express these facts. 
A large number of the structures peculiar to modern volcanic rocks 
are to be found in these ancient lavas, and the presence of these struc- 
tures is sufficient proof of the igneous origin of the rocks, although 
until quite receutly they have been regarded as sedimentary. An almost 
universal characteristic of these South Mountain rocks is the micro- 
poikilitic structure of the groundmass. While this structure frequently 
appears to be an original one, still in most of the rocks under discussion 
there is excellent proof of its secondary nature. Spherulites and per- 
litic parting are also present, sometimes in great perfection, and the 
rock presents in ordinary light the characteristics of a fresh, glassy 
lava. Under crossed nicols glassy structures disappear and the rock is 
seen to be composed of finely granular quartz and feldspar, often show- 
ing poikilitic patches which run across the lines of perlitic parting. "It 
is impossible by any description to carry the definiteness of conviction 
as to the original glassy nature of the groundmass which the character 
of such rock sections justifies. To one who has studied them in both 
ordinary and polarized light, there can be no question as to the second- 
ary character of the holocrystalline groundmass." The structures de- 
scribed are: Fluidal, micropoikilitic, spherulitic, axiolitic, rhyolitic, 
lithophysal, perlitic, amygdaloidal, taxitic and trichitic. 
Since devitrified volcanic rocks are quite common andhave often been 
described, the author thinks best that they should be distinguished in 
some way by name. "If, therefore, we decide to employ this prefix (apo) 
to indicate the specific alteration known as devitrification (Entgla&uvg), 
we may obtain, by compounding it with the name of the corresponding 
glassy rocks, a set of useful and thoroughly descriptive terms, like 
