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THE AMERICAN MUSEUM JOURNAL 



mud brought down into a large basin by a huge river such as the Amazon. 

 Besides being of great extent, this deposit is also of great thickness, in some 

 parts probably as much as 10,000 feet thick. 



If you look upon this area as a series of rocks 10,000 feet thick and 

 200,000 square miles in area, and imagine it the face of a book of the history 

 of the world, you see that it is simply a matter of our turning over the pages. 

 There is not another part of the world that will give the records so com- 

 pletely — a continuous record of the land animals of the world for about 

 three million years. Sometimes we cannot read the record clearly but we 

 can make out most of it. This period is not only very fully recorded but 

 there is no period of the world's history so interesting except the period 

 when man came upon the earth. It is a period when crocodiles, lizards, 



Galepus jouberti Broom, one-half natural size. A complete skeleton of a small member 

 of the Dromasaurians, one of the earliest of the mammal-like reptiles. The head [at the left 

 below] is folded back so that in this photograph it is seen very obliquely but with care all the 

 rest of the skeleton may be easily traced 



turtles and reptiles appeared for the first time; and the study of the records 

 shows us the warm-blooded four-footed forms in the process of evolution. 



The greater part of the Karroo formation lies in the center of Cape 

 Colony. This large area has a scanty rainfall of from five to fifteen inches 

 in the year but as most of the rainfall is due to thunder-storms during a 

 short period, there are usually nine months in which no rain falls, and the 

 vegetation is almost entirely composed of low Karroo bushes. The whole 

 scenery is in many ways strikingly similar to that of Arizona. There are 

 extensive plains that are almost dead level produced by the action of wind 



