182 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



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Fig. 11.27. Evolution of the Franconia quadrangle terrane, White Mountains, N. H. Reproduced 

 from Williams and Billings, 1938. Oal, Albee formation; Oam, Ammonoosuc volcanics; Sc, Clough 

 conglomerate; Sf, Fitch formation; Dl, Littleton formation; bg, Bethlehem gneiss; kqm, Kinsman 

 quartz monzonite; mv, Moat volcanics; ml, Mt. Lafayette granite porphyry; mq, Mt. Garfield 

 prophyritic quartz syenite; eg, Conway granite and Mt. Osceola granite. Bethlehem and Kins- 

 man belong to the New Hampshire magma series. 



the Late or Mid-Ordovician must be revised. Hurley et al. ( 1959 ) report 

 the age of a quartz monzonite stock in northwestern Maine which in- 

 trudes well-documented, fossiliferous, Lower Devonian slate as 360 m.y. 

 The metamorphism of the beds is believed to have occurred along with 

 the intrusion. 



Therefore, the Oriskany sedimentation took place prior to this time. This is 

 in agreement with findings of Fairbairn in Nova Scotia where sediments of 

 similar age have been intruded by granitic rocks . . . (Hurley et al. 1959). 



Ages in the 320-380 m.y. range category have generally been correlated 

 with the Taconic orogeny, but if they indicate Acadian orogeny, then 

 we must conclude that nearly all the metamorphism and most of the 

 plutonic activity is Acadian in New England and the crystalline Pied- 

 mont. 



CARBONIFEROUS BASINS 



Location 



Emerson in 1917 recognized five major Carboniferous basins and a 

 number of minor ones in eastern Massachusetts, southeastern New Hamp- 

 shire, and Rhode Island, and they are shown on the Geological Map of 

 the U.S. ( 1932) accordingly. The new geological map of New Hampshire 

 by Billings (1956), however, recognizes the "Carboniferous" basins of 

 Emerson in New Hampshire as Devonian and older, and therefore it 

 appears that only two major basins are now to be considered, the Nar- 

 ragansett and the Boston. Two smaller basins in northern Rhode Island 

 also are definitely demonstrated, and they will be referred to as the 

 Woonsocket basins, following Emerson. The above basins are shown 

 on the map of Fig. 11.28. 



The Carboniferous stratified rocks are in the slope from the New 

 England upland to the Seaboard lowland and in the lowland itself. 



Narragansett Basin 



The generalized stratigraphy of the three basins shown on the map of 

 Fig. 11.28 is illustrated on the correlation chart of Fig. 11.29. The igneous 

 intrusive rocks are also shown. It will be noted that the basement com- 

 plex consists of metamorphosed Precambrian sediments and intrusives 

 and various Acadian intrusives. Some fossiliferous Lower Cambrian beds 

 are known in eastern Massachusetts (Chute, 1950). 



According to Emerson (1917) the strata of the Narragansett basin 

 are in large part coarse elastics with an aggregate thickness of 12,000 

 feet. At the base is the Pondville quartz conglomerate, which is a coarse, 

 white, granitic waste or arkose 100 feet thick. Above the Pondville is the 

 Wamsutta group of dominantly red conglomerates, sandstones, shales, 

 slates, and felsite flows, breccias, and conglomerates, some 1000 feet 

 thick. Above these strata are the thick Rhode Island coal measures that 

 include dominantly dark gray conglomerate, pebbly sandstone, sandstone 

 and gray wa eke, shale, and coal beds. They contain the Odontopteris 

 flora and insect beds, and are about 10,000 feet thick. Above the coal 

 measures is the Dighton conglomerate of the northern field and the 



