66 IOWA ACADEMY OF SCIENCES. 



as is the case with modern soils. This soil, peat and forest 

 horizon is correlated with the Aftonian interglacial deposits of 

 southwestern Iowa. It has been encountered in hundreds of 

 wells in the northeastern part of the state, and it has been 

 revealed in not a few instances in railway cuttings. The peat 

 and forest bed in the great railway cut at Oelwein was discussed 

 before this Academy* one year ago, and the description need 

 not be repeated at this time. The relations of the beds in 

 question, so far as relates to northeastern Iowa, may be very 

 satisfactorily studied in the extensive reports on well sections 

 in McGee's memoir on the Pleistocene deposits of northeastern 

 Iowa, pages 515-590. 



Buchanan Gravels. — Buchanan gravels were first recognized 

 as a distinct interglacial deposit at the gravel pit of the Illinois 

 Central railway in the northwest . quarter of section 32, 

 Byron township, Buchanan county, Iowa. The j)it is located 

 about four miles east of Independence. The exposure was 

 described.in a paper readtothis Academy two years ago, and the 

 paper, in addition to being published in the proceedings of the 

 Academy, appeared in the American Geologist, f The beds to 

 which the name was applied consist of stratified sands and 

 gravels. The bedding is in places oblique, showing the action 

 of strong currents, and scattered through the deposit are bowl- 

 ders ranging up to 12 or 15 inches in diameter, suggesting the 

 probable agency of floating ice. It is certain that a very large 

 number of the bowlders have not been rolled or abraded, for 

 they retain the facets and scratches due to glacial planing as 

 perfectly as if they had never been disturbed after finishing 

 their journey as part of the subglacial drift transported by the 

 Kansan ice. 



The materials making up the Buchanan gravel have been 

 derived chiefly from northern- sources, though fragments of 

 fossiliferous limestone that has not been transported for any 

 considerable distance are not rare. The materials furthermore 

 have all the characteristics of the pebbles and bowlders that 

 occur in the Kansan drift. A large proportion is dark colored 

 greenstone, with a high percentage of the individual fragments 

 planed and scored. Certain granites and representatives of 

 other rock species are completely decayed, so that blocks a foot 

 in diameter fall to pieces under a single blow of the hammer. 

 Many that were thrown out in the bottom of the pit as too large 



♦Proceedings Iowa Academy of Sciences, Vol. IV, pp. 5*-68, 1897. 

 + VTieric^n Geologist, Vol. XVIl, p. 76. Feb.. 1896. 



