i 3 8 



E. M. KINDLE 



Fig. 2. — Mud-cracks in mud composed of clay 

 and marl. \ natural size. 



the sun. One side of the pan was raised T V inch higher than the 



opposite side, so that 

 near the end of evap- 

 oration the lower side 

 remained moist after 

 the upper side had be- 

 come quite dry, the 

 object being to see 

 what effect, if any, this 

 drying out of the mud 

 in a lateral direction 

 would have on the 

 character of the mud- 

 cracks. The result of 

 this experiment is 

 shown in the photo- 

 graph (Fig. 4), which 

 was made before the 

 lower margin had en- 

 tirely dried, the moist portion being indicated by the darker part 

 near the base of the 

 picture. Instead of 

 the usual reticulated 

 mud-crack lines, most 

 of the mud split up 

 into a set of ribbon- 

 like strips averaging 

 ^ inch in width and 

 having a length of 3 to 

 6 inches. The direc- 

 tion of the mud-cracks 

 which gave this ribbon- 

 like effect was trans- 

 verse to, and evidently 

 controlled by, the zone 



separating the com- 



c ° Fig. 3. 



pletely dried from the size. 



-Mud-cracks in sandy mud. \ natural 



