KATN-DROP IMPRESSIONS 



361 



drops which made them, the force with which the drops fell, and the 

 softness of the mud. If the mud be very soft, it flows and the impressions 

 become obliterated or greatly reduced. About one-tenth of an inch ap- 



FiGUGE 1. — Impressions made hy Rain-drops 

 On tbe left coalescing pits formed by many drops. On the right isolated impressions. 



-^-n — .'*'*» 



Figure 2. — Rain-drop Impressions made on wet Sand 



pears to be the maximum depth. The marginal elevations vary, due to 

 the same factors which control the depths of the depressions. About one- 

 tenth of an inch appears to be the maximum height. The diameters of 

 the depressions vary from about one-half an inch to that of a pin-head 



