396 



SCIENCE 



[N. S. Vol. XLIII. No. 1107 



of aa inch, to four or five inches in diameter. The 

 constituents of the rock are coarse quartz sand 

 grains, quartz pebbles, mica and a large amount 

 of decomposed feldspar. Crossbedding is very 

 prominent, and the conglomerate lies in lens-shaped 

 masses which are tilted in almost any direction. 

 A black carbonaceous layer of a few inches in 

 thickness is also found in the outcrop. The char- 

 acter of the rock at this locality seems to prove 

 conclusively that it is of terrestrial origin and ac- 

 cumulated as fluviatile deposits on piedmont 

 slopes under semi-arid climatic conditions. The 

 origin can best be explained by comparison with 

 the large alluvial deposits forming at the present 

 time in the Valley of California between the 

 Sierra Nevada Mountains and the Coast Range, 

 where a semi-arid climate prevails, where there is 

 a constant large supply of debris for the streams 

 to transport, and where the change of gradient is 

 sufficient for the deposition of the load. In such 

 cases there is an assortment of sediments, the 

 coarser materials being deposited in the piedmont 

 regions while the finer materials are carried 

 farther out. As the deposit seen in the Railway 

 Cut at the locality described is situated on the ex- 

 treme southeastern border of the Newark area in 

 the vicinity of Philadelphia, it is best explained 

 as the work of a stream which flowed into the re- 

 gion from the southeast, the coarse conglomerates 

 representing a phase of alluvial deposition such as 

 is found near the point where the stream emerges 

 from a bordering highland. The crossbedding, 

 such as found here, is a marked characteristic of 

 alluvial deposits made by streams of an arid or 

 semi-arid climate during the period of torrential 

 rainfall. The red color of the rocks and the large 

 amount of decomposed feldspar, also indicate 

 semi-arid climatic conditions. The presence of the 

 carbonaceous layer, the total absence of marine 

 fauna, the ripple marks, sun cracks, animal tracks 

 and the remains of land animals, which have been 

 found in the Newark rocks of the Philadelphia 

 District — all point toward a terrestrial or conti- 

 nental origin. 



The Ordovician- Silurian Boundary in OMo: W. H. 



Shidelee. 



Comparing the proposed new division plane at 

 the base of the Richmond with the commonly ac- 

 cepted division at the top of the Richmond, 14 per 

 cent, of the 395 Maysville species lived on into 

 the Richmond, while not one of the 494 Richmond 

 species lived on into the Medina or Clinton. Of 

 the Richmond genera, 42 per cent, are unknown in 



the Maysville, compared with the 67 per cent, of 

 the Medina and Clinton genera unknown in the 

 Richmond. Three families end with the Mays- 

 ville, fourteen with the Richmond. Three families 

 first appear with the Richmond, while thirty-five 

 families, two suborders, three orders and one sub- 

 class, are introduced in the Medina and Clinton. 

 In Ohio the Belfast beds carry a fauna of Brass- 

 field (Ohio "Clinton") species, so the top of the 

 Richmond is at the top of the Elkhorn beds, and 

 this position is taken as the Ordovician-Silurian 

 boundary. 



A Geological Section of the Lime Creeh Beds of 



loioa: A. O. Thomas. 

 Breociation Effects in- the Saint Louis Limestone: 



Francis M. Van Tuyl. 



The Saint Louis limestone is locally much brec- 

 eiated and disturbed in southeastern Iowa. Two 

 main types of breccia may be recognized: First, 

 an original breccia which occurs both as reefs and 

 as stratified beds in the formation, and second, a 

 subsequent breccia produced by mashing on a 

 large scale in late Mississippian time. Small folds 

 and overthrust faults are associated with the 

 breccia of the last type. 



An Organic Oolite from the Ordovician: Francis 



M. Van Tutl. 



The siliceous oolite which constitutes the transi- 

 tion bed between the St. Croix sandstone and 

 Prairie du Chien dolomite in the Upper Mississippi 

 valley possesses in addition to the ordinary eon- 

 centric and radial structure minute sinuous 

 tubules similar to those which characterize the 

 calcareous alga, Girvonella. 

 The Stratigraphy of Flint Midge, Ohio: Clara G. 



Mark. 



Flint Ridge is located about forty miles east of 

 Columbus and a few miles west of Zanesville, Ohio. 

 It consists of a ridge extending in a general east 

 and west direction and conspicuously higher than 

 the surrounding country. All along its summit 

 may be seen blocks of flint, many of them small, 

 but some large enough to weigh several tons. 

 These blocks of flint appear to be the broken-down 

 fragments of a once continuous ledge. There has 

 been a great diversity of opinion concerning the 

 stratigraphic position of this flint and it has been 

 tentatively assigned to various horizons, from that 

 of the Lower Mercer limestone, to that of the 

 Middle Kittanning, or No. VI., coal. In the spring 

 of 1915 Mr. John Turkopp, a graduate student of 

 Ohio State University, in making a geologic map 



