34 



TE 



Just before entering Sidney (see sheet 7, p. 36) the train passes 



Q 



Sidney, Nebr, 



Elevation 4,090 fe 

 Population 1,185. 

 Omatia414 miles. 



runs 



ern Nebraska, 



confined 



composed at the top of an impure limestone, 



prominent 



mortar 



near Sidney, where the rock is used as a building 

 stone. It has furnished material for the depot and for many of the 

 business blocks and pubHc buildings in Sidney and neighboring towns. 

 Were it not for the pebbles of harder rock that are embedded in it 

 and make cutting difficult, it might be a valuable building stone. 

 The ^^ mortar beds'' constitute the lower part of the Oi^alalla forma- 



on the Brule clay. Both these 



tion 



with 



mations contain fossil bones of extinct mamm 



* The fossils found in the Ogalalla 

 formation show that western Nebraska 

 waa inhabited in late iliocene time by 

 animals of very different types from those 

 living there now, and also that A^ery dif- 

 ferent physical conditions prevailed at 

 that time. In place of the drj-, barren 

 plains of to-day there were numerous 

 streams and swampy lowlands. The fos- 

 sils of the Ogalalla and Arikaree forma- 

 tions are not greatly different and will 

 be described together. Both these for- 

 mations were spread out over a great plain, 

 and it is not surprising to find in them 

 the bones of plains or running animals, 

 such as camels, horses, and deer, as well 

 as of those that inhabited rivers, bayous, 



im 



Although these are called horns, they 

 were really bony protuberances and were 

 probably not sheathed in real horn. 



Camels were common in Xorth America 

 during the iliocene epoch, and several 

 forms have been found. Those of one 

 , ^ „ . genus (Procamelus) were about the size 



and marches. Some of the horses were of sheep and are supposed to be the an- 

 as large as small pomes and were more 

 modern in appearance than theii* diminu- 

 tive Oligocene and Eocene ancestors. 

 They wer6 also more numerous than their 



mal called Syndyoceras (see PL VT, D), 

 whose headdress equaled or outdid in 

 grotesqueness that of its Oligocene ances- 

 tor Protoceras (see PI. VII, E, p. 41). 

 Its head somewhat resembled that of an 



T 



antelope but was longer and had foiu" 

 horns, the larger pair, over the eyes, 

 curing inward and the smaller pair, 

 nearer the muzzle, curvin^: outward. 



cestors 



Others were large and had long necks 



giraffe 



All these 





ancestors, and their f 

 several widely 



The Arikaree cont-ains great numbers of 

 bones of a peculiar type of animals 

 called chalicotheres. They were larger 



horse and had a horseKk 



ancient camels had hoofs like cattle, 



head, long front legs, and shorter hind 

 l^s, but every foot had three toes, each 

 of which in place of a hoof bore an enor- 

 mous claw. One of the forms, known as 

 Moropus (see PL VI, C, p. 40), was 

 strangely grotesque. An equally strange 



represent not cushioned feet Hke those of the cam- 

 els of the present day. 



Rhinoceroses were abundant in Mio- 

 cene time. Hundreds of specimens of 

 Teleoceras, a very heavy bodied, short- 



(see PL VI, ^),have been 





Mm ^^„ 



found . The 





^ / - ■ ' - — - 



elephant is the best-known type and the 

 only living representative, became promi- 

 nent during the :VIiocene epoch, when a 



called 



nun 



