132 A. Mil ward, Esq., 07i an Extensive Mud- Slide 



these wrinkles are formed, or what law they follow. Varia- 

 tion of consistency in the mud, arising from atmospheric 

 changes, or other causes, may be supposed to have some 

 effect ; but the evident approximation to a certain regularity 

 in the alternations of bands, would seem to point to some 

 more regular agency. 



If we may judge from the absence of bands in No. 5 on 

 the drawing, which is distinguished from the other streams 

 by having no steep flow at the commencement, the steepness 

 of the first descent may be connected with the phenomenon. 

 However this may be, the occurrence of these ridges in the 

 second example is a fact, and they have every appearance of 

 being a general phenomenon, not dependent on local pecu- 

 liarities of resistance or obstruction. 



Upon examination of the second example, it appeared clear 

 to me, that the smooth mud owed its finer quality in a great 

 degree, if not wholly, to the drainage water from the ridges 

 above, holding in suspension the finer particles. The water 

 naturally deposits this fine matter on the less-inclined inter- 

 vals ; and thus the intervals between the ridges become 

 smooth at the expense of the latter, which are left com- 

 paratively rough. 



I am of opinion that in the first slide the extreme satura- 

 tion of the mud, arising from accidental circumstances, 

 allowed the surface to subside into a slope, so as to conceal 

 the mode of formation. 



It is not at all impossible, that a subsidence may take 

 place in the second mud-slide also ; for on thrusting my stick 

 through the upper crust, which had been dry for some two 

 months, I found on withdrawing it, that the water dripped 

 from its extremity. It cannot be expected to subside en- 

 tirely, as it never could have been so wet as the mud of the 

 first slide. 



2. The second peculiarity which I have to remark is the 

 appearance represented at d on the drawing, in the stream 

 numbered 3. The curved bands are here seen to be broken 

 up on account of the steepness of the descent; and yet be- 

 low, when the angle of elevation diminishes, they reappear 



