SID PASISCANMEICNI IM OQRCAIEL AAMITEII ACAI ILI TITBISA IETS, 
val (?), (6) diabase flow, and (7) erosion interval. The different lavas have 
been folded, faulted, and secondary structures have developed within them. 
Metamorphism was most extensive in the diabase, which has become a well- 
developed schist. The quartz-porphyry is the least altered. 
Merrill* describes the disintegration of the granite rocks in the District 
of Columbia, and finds from chemical analyses, calculated on a water-free 
basis, that they are very similar to those of the original rocks, and therefore 
that the rocks are as much disintegrated as decomposed. The chief chemical 
change is hydration. 
Haworth? maps and fully describes many areas of pre-Cambrian crys- 
talline rocks of Missouri. These occur in irregular areas and isolated hills 
extending over an area seventy miles square in the southeastern part of the 
state. The rocks consist of granites, granophyres, and porphyries, which are 
occasionally cut by diabase dikes. Some of the granophyres are located 
between the granite and the porphyry areas, and seem to be a connecting link 
between them. At other times they are in contact only with the granite or 
with the porphyry, in which case the connections are traceable in one direction 
only. It is concluded that all are different facies of a magma belonging to a 
single period of igneous activity. Associated with the pre-Cambrian are clastic 
beds occupying small areas, as for example, at the summit of Pilot Knob. 
Hill? finds in Indian Territory in the heart of the area occupied by the 
Chickasaw Nation, a granite called the Tishomingo granite, which appears to 
be of pre-Palzeozoic age. 
Russell# finds as a result of a geological reconnoissance in central Wash- 
ington that in Okanogan county there are granites, schists, quartzites, and allied 
rocks. Resting upon the upturned and eroded edges of these crystalline 
rocks is the Kittitas series, which belongs to the Tertiary system. 
Iddings, Weed, and Hague$ describe and map the geology of the Living- 
ton sheet, Montana. Archean crystalline rocks constitute a part of the south- 
ern half of the region. These include mica-schists, phyllite, gneiss, and 
granite. Much of the granite is eruptive and carries angular blocks of other 
t Disintegration of the Granitic Rocks of the District of Columbia, by GEORGE P. 
MERRILL, Bull. Geol. Soc. Am., Vol. VI., 1895, pp. 321-332, Pl. XVI. 
2 The Crystalline Rocks of Missouri, by ERasmMus HAworrTu, Missouri Geol. 
Sur., Vol. VIII., 1895, pp. 84-222 with map and plates. 
3 Notes on a Reconnoissance of the Ouachita Mountain System in Indian Territory, 
by R. T. Hitt, Am. Jour. Sci. (I1I.) Vol. XLII., 1891, pp. 11-124. 
4A Geological Recoinoissance in Central Washington, by I. C. RussELL, Bull. 
108, U.S. G.S., p. 20, with map. Washington, 1893. 
5Geol. Atlas of the U. S., Livingston, Folio No. 1, by J. P. IppIncs, WALTER H. 
WEED, and ARNOLD HAGUE, U.S. Geol. Sur. Washington, 1894. 
