RECORDS OF MEETINGS OF 1908 491 



mentary series. The limestones of the area, therefore, are separable into at 

 least two widely different types — one type belonging to and of the same age 

 as the Fordham, all of the others much later and possibly themselves complex. 



At that time, however, no interbedded limestones were known as such 

 in New York City, the type locality of the true Fordham. The author 

 announced the discovery of such beds at three different points within the 

 city during the past summer. One of these at Jerome Park Reservoir and 

 205th Street had been previously mapped and heretofore interpreted as a 

 small in-fold, a closely pinched syncline, involving some of the overlying 

 Inwood Limestone in the closed trough. Recent excavations at this locality 

 show that the calcareous beds stand almost vertical and are perfectly con- 

 formable to the banded structure of the rather micaceous Fordham on both 

 sides. The total width of the calcareous beds is about 27 feet. Nearly 

 central is a 7 X 10 foot bed of much more massive Umestone than either 

 flank. Altogether there are no less than 26 alternating measurable bands 

 or layers of serpentinous and chondroditic coarsely crystalline dolomite 

 limestone and a quartzose schist. Of the thirteen bands of quartzose 

 schist, eight are on one side of the large central limestone bed and five on 

 the other. The thicknesses of the successive corresponding bands on oppo- 

 site sides likewise do not agree. These facts are taken as sufiicient evidence 

 that the occurrence is a true interbed. The mineral chondrodite is 

 abundant. 



The other two cases are even more decisive as to relation. They are 

 both on 196th Street, east of Jerome Avenue. In one the narrow limestone 

 bed is part of a simple anticline in which the association of beds is such as to 

 exclude any possible connection with an overlying formation. Two other 

 beds are separated from each other and this by typical micaceous Fordham. 



The Fordham, therefore, at its type locality does carry interbedded 

 limestones similar to those in the gneisses of the Highlands, and these beds 

 are much older and entirely distinct from the overlying Inwood. 



Professor Grabau said in abstract: Since the early ideas regarding the 

 formation of sedimentary rocks developed in the British Isles, it is not 

 surprising that geologists have so generally come to regard all strata as 

 either marine sediments or deposits found in fresh-water lakes. Only when 

 the extensive desert areas of the world came under the observation of geolo- 

 gists, chiefly from the continent of Europe, was an attempt made to interpret 

 the history of stratified rocks by an application of the new lithogenetic 

 processes thus observed. In this work German stratigraphers have taken 

 the lead, though physiographers were among the first to insist on the more 

 rational interpretation demanded by the characteristics and structure ofjthe 

 formations in question. While the Jura-Trias rock beds of western North 



