hedliCka] skeletal REMAINS' OF EARLY MAN 257 



The relative ages of these possible occurrences would be somewhat 

 as follows: The last-mentioned (accidental burial), taking place 

 during the growth of the gullies would be the latest, and in the 

 writer's estimate, would not be more than half a century old, as the 

 gullies are probably not of greater age. The second (intentional 

 burial) would probably antedate the cemeter}" of the church, which 

 is said to have been established a hundred years. The first would 

 date back to the" formation of the deposit. The source of the mate- 

 rial in the river bed, the winds to transport it, and the plain of deposit 

 are favorably related at the present time. The formation is geneti- 

 cally related to them and may be ascribed with confidence to the pres- 

 ent geologic epoch. 



In the superficial loess were found the jawbone of a horse and the 

 remains of a human skeleton, at points about 100 m. apart, in the 

 nearly vertical sides of a gully which passes just south of and close by 

 the village of Sotelo. 



The jawbone of the horse lay in the gray loess at a depth of slightly 

 less than 3 m. (about 9 feet) below the surface (pi. 23). The front of 

 the jaw was buried 18 cm. in from the face and the articular process 

 about 10 cm. Only about 1 cm. of the lower edge was exposed when 

 found. The loess above the jaw appeared laterally continuous with 

 that on each side and in firmness and structure exhibited closely 

 similar if not identical characters. Close examination detected 

 rounded loess pebbles or concretions of darker color than the mass, 

 which did not occur in the adjacent loess and which might indicate a 

 secondary deposit. The bone was that of a modern horse. 



If we may regard this jawbone as a fossil indigenous to the loess, 

 the latter is more modern than the writer would otherwise infer. If 

 it represents a case of accidental burial, it is related merely to the 

 growth of the gully and probably somewhat in the following manner. 



When a pool of water gathers on a surface of loess, as it may in a 

 shallow hollow during a rain, and sinks in, the water has a capacity 

 for mixing with a considerable proportion of loess and rendering it 

 fluid. This capacity depends on the fineness of grain of the loess 

 particles which may be contained in the thickness of a capillary 

 film and thus become part of the liquid. The mixture flows like a 

 fluid. When such a mass finds an exit at a lower level, as in a gully, 

 it flows out and leaves a vertical pit having a horizontal outlet at the 

 bottom. The writer saw a number of such pits in the loess of China 

 and thinks they might readily form in the loess at Sotelo, although 

 he did not observe any in the small area inspected.* 



It is easy to understand that a bone might fall into such a pit and 

 become buried by loess blown from the immediate forination. There 



' They were seen later by both the writer and Doctor Hrdlidka in loess banks in Argentina. 

 21535°— Bull. 52—12 17 



