230 APPENDIX. 



stone country, and by the many undulations in the uncovered 

 limestone which we have already had occasion to mention. 

 From the observations made on the 18th, it was thought very 

 probable that all the hills observed at a distance on the 17th, 

 were formed of this sandstone ; and from some characters 

 which had appeared at the time to present an anomaly it was 

 inferred that the Enneshoteno or Twin Mountains, near 

 which we had passed that day without stopping, were proba- 

 bly also remains of the general sandstone formation which 

 extended over the whole country. No organic remains were 

 observed in the sandstone, or in the limestone which under- 

 lays it, but no doubt can exist that they may contain some, 

 and that the limestone probably contains many. 



" Proceeding towards the Wisconsin, the country presents 

 an alternation of rolling and undulated prairie, interspersed 

 with hills composed of either one or the other of these rocks. 

 The sandstone is found in most places to be covered with 

 thin, flattened fragments of a stone differing in its nature 

 and texture from the character of the other rocks, whether 

 of limestone or sandstone. These fragments are generally 

 observed to vary from three to twelve inches in length, from 

 two to eight in breadth, and from one quarter to one inch in 

 thickness. They present appearances of having been wea- 

 thered, but not of having been rolled. They are very abun- 

 dant, and we could account for them in no other way than by 

 admitting that they were the remains, probably the harder 

 parts of a stratum that had at one time covered the sand- 

 stone, but that had disappeared almost entirely, leaving only 

 these fragments to attest its former existence and situation. 

 On examining these fragments w^ith care, we found them to 

 be very uniform in their characters. Their composition is, 

 in great measure, calcareous, but from their greater hardness 



