1863.] 201 [Lesquereux. 



Remarks concerning the nature and variety of the Millstone Grit of 

 Arkansas, are noted many times in my diary. Thus, I read : Pass- 

 ing the hills or divide between the affluents of White River, I find 

 the Millstone G-rit of still more varied appearance. Sometimes it is 

 a coarse, hard sandstone, a compound of fine grains of quartz, true 

 millstone grit very hard, and in thick banks. These are separated 

 or underlaid by soft, easily disintegrated, shaly sandstone, and thus 

 they break in large massive banks or pieces thrown down along the 

 slopes of the hills, or in the narrow valleys. Sometimes the same 

 formation is mostly a compound of shaly sandstone, alternating with 

 ferruginous shales, separated by thin beds of clay iron ore, or even 

 of hard fireclay, without any trace of conglomerate. Sometimes the 

 sandstone becomes black, ferruginous, and is here and there cut by 

 a narrow streak of conglomerate, whose quartz pebbles are rarely 

 larger than a small hazel-nut, generally much smaller. The Millstone 

 Grit-measures are for more persistent in their thickness in Arkansas 

 than in the East, and as the top of it has not been seen anywhere, 

 the highest mountains being too low, it may be supposed that its 

 thickness is greater than it has been measured at Horsehead Moun- 

 tain. 



Of course, though the variety of appearance and the great thick- 

 ness of the Millstone Grit of Arkansas can be compared with some 

 parts of the coal-measures of Nova Scotia, referred by geologists of 

 that State to true coal-measures, we cannot conclude an identity of 

 formations. From what you published in the Proceedings of the 

 Society, I agree with you, and readily believe that the Nova Scotian 

 basin is a separated member of our great American coal-fields. The 

 flora of both the Canadian and the United States coal-fields is appa- 

 rently the same. At least, of all the plants published by Bunbury, 

 too few in number, indeed, to permit a satisfactory comparison, there 

 is now no one that has not been found in our coal-fields. Odontop- 

 teris cimeafa, Bunb., was for many years unknown in our coal-mea- 

 sures, but I have found it in plenty two years ago at Murphysboro', 

 Illinois. This and a few other of Bunbury's species have not been 

 found in Europe. But contrary to our opinion, we have these facts, 

 that the anthracite basin of Pennsylvania is from all appearance the 

 shores of a coal-basin. That Dawson finds in Canada an abundance 

 of fossil coniferous wood ; that the English naturalists assert that 

 such wood is also in plenty in the coal-measures of England, while I 

 can find none in ours ; that also from Dana's assertion, the fauna of 

 the coal-measures of Nova Scotia is rather related to that of Endand 



