No abstract

Joesmithite has 23 atoms in the asymmetric unit, presented P. B. MOORE A comparison of Grenville and Lewisian granites IT is generally agreed that for a given cycle of plutonic activity Older granites tend to be rich in sodium relative to potassium, while younger ones tend to be rich in potassium relative to sodium (Read, 1949, pp. 148-149). Bowes (1967) has demonstrated a compositional trend of this kind for Lewisian granites, which he interprets in terms of Read's Granite Series.

M AJOR objectives of this study have been to define the character of the igneous rocks present; to determine the number of separate igneous complexes, their relative ages, their variations, the relationships of these variations to structure, and the interpretation of their origin; to elucidate the mechanics of intrusion; and to discriminate primary magmatic structures from postconsolidation metamorphic features and to describe and interpret the mineralogic facies as a result of metamorphism.The oldest rocks of the region are crystalline schists, gneisses, granulóse rocks, marbles, quartzites, skarns, and amphibolites of the Grenville series.A concept widely held is that the Grenville series was invaded by granite during an early, if not the earliest, period of magmatic intrusion in the Adirondacks, but the present conclusion is that no really satisfactory unequivocal proof for the existence of this older granite intrusion in the northern and northwest Adirondacks, at least, has yet been presented, though it may well be present.The anorthositic series of rocks constitutes the earliest intrusives proven to be developed on a large scale. Both the main mass and the outlying intrusive rocks show a similar development of finer-grained granular border facies more mafic Adirondack Igneous Rocks lined grains) has a systematic regional variation, and, concomitantly, there is a consistent variation in the mineralogic facies developed by reconstitution in each type of rocks within the different regions. If the interpretation of the Diana and Santa Clara complexes as gravity-stratified sheets is correct, the deformation of these rocks must have occurred after their consolidation, for thorough-going crush structures are not known in sills undeformed by orogenic stress, and, in the Adirondacks, sills of quartz syenite and granite, preserved in limestone which has acted as a cushion, are undeformed even in areas where crushing and recrystallization are normally intense. The trend lines of the foliation and the linear structure, the different physical facies, and the different mineralogic facies all have a systematic regional development consistent with an interpretation of origin in terms of dynamothermal metamorphism, in terms of variation in depth, temperature, and stress. Four belts of metamorphism are defined: (1) Cataclasis predominant; (2) crushed and recrystallized without production of garnet; (3) crushed and recrystallized with formation of garnet; and (4) two large cores of gneissoid relatively uncrushed, unrecrystallized rock. All the igneous rocks, with the probable exception of part of the younger granites, are thought to have been wholly consolidated at the time of the metamorphism, and their foliation and linear structure, as now found, are products of plastic flow of solids. The foliation of the granites is in part primary gneissoid, in part protoclastic, and in part due to crushing and recrystallization in the solid state. The relative importance of these factors is widely variable.

Grenville lowlands______________________________ Fall zone belt __________________________________ Childwold rock terrace __________________________ Adirondack mountain section.____________________ Ellenburg Mountain range___________________ Santa Clara trough. ________________________ Lyon Mountain range,______________________ Saranac trough ("Lake belt")________________ Mount Whiteface range _____________________ Mount Marcy cross range____________________ Origin of topography____________________________ Relation of topography to tectonic history_________ Pre-Paleozoic surface of,low relief____-________ Taconic doming and faulting.________________ Frontenac axis and Grenville lowlands_________ Fall zone monocline--_______________________ Childwold rock terrace__-___--_-_____-___ Block faulting and warping._________________ Mesozoic peneplain_________________________ Tertiary doming, renewed faulting, and erosion. Tertiary (?) or Cretaceous (?) erosional terraces __ Relation of topography to bedrock._______________ Kind of rock_______________________________ Layering and foliation_______________________ Fractures.

__________________________________________ Introduction and acknowledgments.__________________ Geography. ________________________________________ Previous work._____________________________________ Rocks of metasedimentary origin _____________________ Marble or metalimestone________________________ Quartz-potassium feldspar and associated gneiss____ Pyroxenic gneiss._______________________________ Garnetiferoxis gneiss and amphibolite____________ Hypersthene-quartz-oligoclase gneiss______________ Biotite-quartz-feldspar and associated gneiss_-__-Epidote-scapolite-quartz gneiss and associated rocks. Miscellaneous gneiss.___________________________ Stratigraphy of metasedimentary gneiss.______________ Orthogneiss._______________________________________ Metagabbro gneiss._____________________________ Syenite gneiss._________________________________ Igneous rocks._____________________________________ Pyroxene syenite, pyroxene granite, and pyroxene alaskite series._______________________________ Petrology.._-______-__________._____ Sparta Lake belt__________________________ Ford belt.__.-_- .-______.____.___________ Holland belt.______________________________ Hyper«thene granite, _______________________ Hornblende granite and alaskite__________________ Rocks of uncertain origin-___________________________ Amphibolite_ ___________________________________ Quartz-oligoclase gneiss._________________________ Biotite-quartz-oligoclase gneiss._______________,..._ Albite alaskite________________________________ Quartz-microcline gneiss.________________________ Dikes.____________________________________________ Petrogenesis ______________________________________ Pyroxenic gneiss._______________________________ Quartz-potassium feldspar gneiss and associated epidotic gneiss._______________________________ Quartz-oligoclase rocks._________________________ Hypersthene-quartz-oligoclase gneiss__________ Quartz-oligoclase gneiss (Losee Gneiss)________ Amphibolite_ _ ________________________________ Quartz-microcline gneiss.________________________ Hornblende and pyroxene syenite orthogneiss_____ Granitic and syenitic rocks_______________________ Metamorphic facies_____________________________ Franklin block.____________________________ Beaver Lake block__________________________ Ryker Lake block_________________________ Comparison with nearby areas._______________