EASTERN TRIASSIC BASINS 



131 



moved by erosion, but the evidence is not available to support such a view 

 (Stose and Stose, 1944). 



Border Conglomerate. Along the northwest border of the Triassic 

 basin occur deposits of fanglomerate, generally called conglomerate and 

 breccia. They make up the "Border conglomerates." In width of exposure 

 they range from less than half a mile to about 8 miles and lie in discon- 

 tinuous patches along the Precambrian and lower Paleozoic rocks of the 

 northwestern border. The largest area is south of Reading, Pennsylvania, 

 which extends across the Gettysburg (Brunswick) formation to the New 

 Oxford (Stockton). Most of the gravel fragments were derived from 

 Lower Paleozoic limestones, dolomites, sandstones, and quartzites, but 

 some came from beds as high as the Devonian, and some are Precambrian 

 rocks. In one place Triassic basalt forms boulders and cobbles in the 

 fanglomerate (Carlston, 1946). 



The Border conglomerate is for the most part of Brunswick age, and as 

 depicted in certain cross sections is the top and youngest layer of the 

 Triassic group. It seems to lie unconformably across the older Triassic 

 beds in places, and in others rests directly on the pre-Triassic. On the 

 other hand, the conglomerate beds pass into sandstones and shales and 

 are undoubtedly mostly a northwestward marginal facies of the Bruns- 

 wick. Even Border conglomerate wedges have been observed in the Stock- 

 ton and Lockatong, and although the conglomerate is chiefly of Bruns- 

 wick age, local bodies of it may be of any age within the Newark group 

 (McLaughlin, 1931, 1958). 



Although the Border conglomerates clearly betray a northwest origin, 

 most of the material washed into the Triassic basin is thought to come 

 from the southeast. The reason, according to Stose and Bascom ( 1929 ) 

 lies in the composition of the basin beds. The "poorly assorted arkosic 

 grits, containing feldspar and mica derived from disintegrating granitic 

 rocks" were exposed, they believe, only in the land southeast of the basin. 

 Except for a stretch of about 75 miles in southeastern Pennsylvania to 

 which Stose and Bascom refer specifically, the Triassic basins in the Pied- 

 mont are bordered on both sides by crystalline rocks that could have sup- 

 plied feldspar and mica, but the Paleozoic pebbles in the border con- 



glomerate indicate that little Precambrian was exposed on the northwest 

 at the time of Triassic deposition in the southeastern Pennsylvania area. 



Deep River Basin 



The Deep River basin is in North Carolina and is generally regarded 

 as made up of the Cumnock basin on the southwest and the Durham 

 basin on the northeast. The southwestern basin is noted for its Triassic 

 coal. The deposits in these basins are much like those of the New ark basin 

 with an abundance of gray arkosic beds lensing into red sandstones and 

 shales and gray to buff sandstones. Locally thin carbonaceous shale beds 

 occur. Conglomerates, fanglomerates, and in places landslide breccias 

 mark the border zones, but here, unlike in the Newark basin, both bor- 

 ders are marked by the coarse deposits. Thin conglomerates with an abun- 

 dance of quartz pebbles occur also in the central areas (Prouty, 1931). 



The torrential fanglomerates are more voluminous along the eastern 

 margin of the basin than the west, which shows that the eastern margin 

 was the steeper and that an area of land existed there as well as on the 

 west. 



Connecticut Valley Basin 



The Triassic sedimentary rocks of the Connecticut Valley are all clastic 

 and, if anything, coarser than those in New Jersey, Pennsylvania, and 

 Maryland. Red colors dominate, and they are also interlayered with trap- 

 rock sheets. The basin is bordered in part on both sides by faults, and is 

 thus a graben; but the eastern fault is by far the greatest and is known as 

 the Great Fault. All beds dip generally eastward into it, as the beds dip 

 generally westward into the border fault of the Newark basin. See map 

 of Fig. 9.3. The Great Fault has a throw estimated variously between 

 17,000 and 35,000 feet, but the basin beds and floor have not been re- 

 garded in the same way as Bascom and Stose conceived the structure of 

 the Newark basin. As diagrammed in the cross sections of Fig. 9.4 the 

 throw would be of the great magnitude mentioned, but if diagrammed as 

 it is in Fig. 9.2, the displacement would be much less. 



According to Krynine (1941a) the wedge of sediments is built of coa- 



