BIG COTTONWOOD FORMATION 233 



Pieces of carbonized wood and leaves occur quite generally in the upper 

 or sandy part of the formation, and in a few places very good fossil leaves 

 were collected. Brown, soft sandstone and ferruginous concretions of 

 very local and limited development contain the leaves. At the north side 

 of the river, in the southeast corner of section 34, Milford, Brown county, 

 is where the specimens described by Lesqu.ereux (5) were found. I have 

 collected also in the northwest i/4 of northeast y^, section 36, Milford, and 

 in the center of section 31, New Ulm. At the south end of the Minne- 

 apolis and Saint Louis railway bridge over the Big Cottonwood many good 

 specimens were found. This is the very top of the formation, while the 

 other localities are variously in lower position. The last-named locality 

 is evidently where James Hall collected leaves which Lesquereux later 

 identified. At this place a species of Pelecypod was also found by Mr 

 Juni. Pieces of wood occur in lower strata and even in the limestone. 

 In the limestone at Heimann's limekiln and at Winkelmann's there are 

 undescribed Algal secretions, similar to the Schizothrix, which builds lime 

 in the lakes of Minnesota in recent time. The fossil Algal skeletons 

 appear as nodules made up internally of laminae of granular lime, with 

 open, clay-filled, or calcite-filled intervals between them. 



A description of the Big Cottonwood formation from place to place 

 would be very much detailed, owing to the many changes and exceptions 

 to any rule which might be given, but a few places are instructive. In 

 one place on the Big Cottonwood river (northwest i^, of northeast %, sec- 

 tion 86, Milford), where the rotted granite, as before described, rises 10 to 

 15 feet above the river, about 40 feet of sand belonging to the "Big Cotton- 

 wood formation is seen between the granite and the glacial drift. In 

 other places along the river the formation is thicker by reason of the sur- 

 face of the granite being lower. There is generally 50 feet of strata 

 above the river level. At New Ulm the top is at about 870 feet above 

 tide — that is, 75 feet or less above the river at high water — and the for- 

 mation is over 200 feet thick. At Bedstone village the strata of limestone 

 and shales are in contact 'with the Courtland quartzite. " The same strata 

 extend thence under the meadow land to the small creek which passes 

 Heimann's lirnekiln and some distance toward, if not to, the New Ulm 

 quartzite conglomerate. From the creek eastward along the wagon road 

 up the hill, shales and clay are evident to the height of about 875 feet 

 above tide. A complete section is not shown distinctly here, but from 

 the bottom of the creek to the top of the section there appears to be (a) 

 limestone, 2 feet; (6) clay, 20 feet; (c) limestone, 2 feet; (d) shale 

 mixed with limestone, 15 feet; (e) clay, 20 feet; (f) limestone, 1 foot; 

 (g) clay or shale, 20 feet. Sandstone is not seen. The • limestone is 

 "nodular" or "concretionary/' consisting largely of lumpy Algal secre- 



