68 STUDIES FOR STUDENTS 



bad cases makes a good case. On the contrary, the multiplica- 

 tion of weak and false cases throws doubt on all and is a legiti- 

 mate ground for rejecting all. The first step toward a firm 

 ground of confidence is the sweeping away of all bad cases 

 of the past and the effectual barring out of all new ones. 



The interpretation of imbedded and striated relics. — Human 

 relics found in the true glacial deposits, whether striated or not, 

 do not necessarily tell whether man lived in the immediate pres- 

 ence of the ice or whether he had lived in the region before the 

 ice invasion, (i) The relics may have been picked up from the 

 preglacial surface by the ice as it pushed over the region, just as 

 rock fragments and earthy matter were, or (2) they may have 

 been dropped on the ice or at its border or on the moraines in 

 the presence of the ice. If the relics are found to be associated 

 with other organic remains that imply a warm climate, the 

 former inference is favored ; if the associated organic remains 

 imply a cold climate, the latter inference is the more probable, 

 but as all the relics are disturbed, the inference is not firm in 

 either case. If human bones are found that show evidence of 

 long weathering and subsequent striation, there is good ground 

 for inferring the existence of man in the previous interglacial or 

 preglacial period. The absence of weathering would not be 

 equally good ground for the opposite inference, because certain 

 kinds of burial exclude weathering. 



A demonstration that man existed before a given glacial inva- 

 sion would imply his existence during it in some part of the 

 globe, and presumably in the grand division in which the relics 

 were found, but a closer interpretation than this requires special 

 evidence. 



II. EVIDENCES FROM THE INTERGLACIAL DEPOSITS. 



The interglacial deposits include those surface accumulations 

 that were formed in the interval between the ice invasions of a 

 given region. They are chiefly soils, muck, peat beds, and 

 various wash products, including fluvial, lacustrine, and occasion- 

 ally marine clays, silts, sands, and gravels. There were similar 

 deposits outside the glaciated regions, but as these were not 



