50 NEW YORK STATE MUSEUM 



This section does not correlate with any of the beds seen in the 

 Ogdensburg section, where there is nothing resembhng such a 

 thickness of thin-bedded, flinty dolomites, wholly unmixed with the 

 granular, dark-blue beds with calcite cement which make the larger 

 part of the upper section there. We are therefore forced to con- 

 clude that this section lies above anything seen at Ogdensburg, and 

 that it can not be much higher. The dip in the district is to the 

 north, as will be shown; but it is not high. Red Mills is about 3 

 miles farther north than Ogdensburg, and 6 miles farther east. 

 The summit beds of the section at Ogdensburg are 80 feet above 

 the river. Judging from the rate at which the Heuvelton and the 

 lower Ogdensburg beds pass beneath the river level between MorrisT 

 town and Ogdensburg, and assuming that the rate remains the 

 same below Ogdensburg, the upper beds of the Ogdensburg section 

 should have just about reached the level of the river at Red Mills. 

 We feel therefore reasonably secure in stating that this thin-bedded 

 dolomite zone at Red Mills almost directly overlies the beds of the 

 Ogdensburg section, and that their 20 foot thickness should be 

 added to the thickness of the formation. 



Elsew^here on the Red Mills sheet outcrops are exceptional and 

 show no great thickness of rock. But all the outcrops seen are of 

 the same type of rock as at Red Mills, hard, flinty, fine-grained 

 dolomite. The rock is very unfossiliferous, not a sign of a fossil 

 having been seen on the Red Mills quadrangle. In this respect 

 also the rock differs from the lower beds shown west of Ogdens- 

 burg. The most northerly exposure seen, on Rockaway point, 

 north of Tilden, is nearly 5 miles farther north than the section 

 at Red Mills, and should therefore represent a considerably higher 

 horizon. A single, massive bed of gray, flinty dolomite is, however, 

 all that is shown. 



Summary of section of Ogdensburg formation. The reporting 

 of detailed sections furnishes a dreary job for the general reader, 

 hence the details are here briefly summarized. 



Between Morristown and Ogdensburg all the beds of the lower 

 portion of the formation are shown, with a thickness of some 120 

 feet. The base lies unconformably on the underlying beds, and 

 the lower beds contain sand grains. Some 15 feet of granular, 

 blue, calcareous dolomites follow, then 20 feet of thin-bedded, 

 fine-grained, gray beds, weathering brown. Above come 80 feet 

 of alternating dark-blue, granular beds, and dark-gray, more finely 

 granular beds, of dolomite w^ith calcite cement. All the beds are 



