DISTRIBUTION— UNITED STATES 625 



near the railroad station at Great Notch, a distance of four miles. The 

 superficial exposures of pillowy basalt along this course vary from 100 or 

 200 feet to more than 1,000 feet in width. There is no indication of an 

 ending of the structure at either extremity of this belt, but the thick and 

 almost continuous covering of glacial drift for several miles northeast of 

 Paterson and southwest of Great Notch has thus far prevented the iden- 

 tification of the structure beyond the points named. 



Pillow structure is exposed in great perfection of development in the 

 trap quarries of West Paterson and Great Notch (plates 15, 16, and 17, 

 figure 1), where it extends to the full depth of the quarries, and the bot- 

 tom has not been reached. Fifteen miles farther southwest a precisely 

 similar structure has been exposed to only a shallow depth in the same 

 ba-salt sheet (but at the upper surface instead of near the middle) by a 

 small ravine and the old prospecting pits locally known as the "copper 

 mine," near Glenside Park (formerly Feltville), 2 miles northeast of 

 Scotch Plains (figure 2, page 628). 



In contrast with these occurrences, the pillows of Second Mountain 

 occur at the bottom of the great basalt sheet. At Little Falls they are 

 exposed at the northeast corner of the new concrete reservoir of the East 

 Jersey Water Company, and may be seen at short intervals northward 

 along the eastern border of the trap for more than half a mile. The pil- 

 lows attain maximum diameters of 2 to 3 feet and, again in contrast with 

 those of First Mountain, are for the most part markedly vesicular. They 

 are coated with the characteristic glassy (tachylitic) crust and form ac- 

 cumulations 10 to 20 feet thick along the old quarry walls and in the 

 cliif s. In places they form the bottom of the sheet next to the underlying 

 i^d sandstone, which was formerly quarried extensively along this con- 

 tact, and elsewhere they rise 10 feet or more above the base, the latter 

 consisting in such places of normal basalt jointed into small wedgy and 

 splintery columns. 



The exposures at West Paterson and Great Notch are particularly fine. 

 In grading the streets of Paterson the rock has been cut along McBride 

 Avenue from Eockland Street to Howard Street (near the right bank of 

 the Passaic Eiver, three-eighths of a mile above the falls), exposing excel- 

 lent examples of pillow structure with nearly circular cross-sections in 

 places (plate 15), but also showing ellipsoidal and long-drawn-out bolster- 

 like masses. The common interstitial tachylite breccia, with calcite, 

 quartz, zeolites, etcetera, has been weathered out so completely as to ex- 

 hibit very clearly the spheroidal, boulder-like appearance of the pillows. 

 Later excavations have modified the exposure along this street somewhat, 

 but it still shows both the curved surfaces and the cross-sections of typical 



