224: Jill Aimrii-dii ( i < iihiij 1st . Ottobcr, IH!)! 
to tilt' (iiuirt/c ()iitcT()|) of the 'rrciulvvcll iniiie, svnd covered Ity :i 
lliin layer (»f siind and clay. This was l)r<)U<j;lit to my notice l»y 
Mr. J. McDonald ("alderwood, sMpei'iiitendcnt of the 'rreadwel! 
mine, on |)onulass island. o|)})osite .Juneau. The corals were found 
about 2(10' above tide. Dr. W. 11. Dall identifies it as a Paracy 
athus. agreeing well witii the untigui-ed /'. sliKd-nxii \'errill, from 
.Monterey. Tie thinks it ini[)robable that it can exist in the cold 
.Vlaskan waters at the present day, though little is known of its 
distribution, and regards the specimen as probably I'leistocene. 
The ef)ral became attached to the njcks when the region was de- 
pressed at least 200 feet below its prescuit level, and during an ap- 
l)arently somewhat warmer [)eriod which followt'd on the heels of 
the great ghiciation of the region. This agri'i's well with the evi- 
dence furnished by the forest, which also shows at least a small 
amount of oscillation accompanying the I'cceiit small glacial ad- 
vance. 
DISlNTKdRATlON Ol-' TlIK RO(n\'S .VROUNK .\HI1{ (iL.VClKR. 
ha iiiiKiinit. — The rapidity with which the rocks of this vicinity 
disintegrate is very great. This however is much more true of 
the slate mountains than of those of limestone or diorite. The 
fissured condition of the rocks is a. powerful aid to the ordinary 
disintegrating agencies which operate in high latitudes and on 
high mountains. The [)iles of debris that have accumulated 
since the retreat of the glacier are astonishing, considering the 
shortness of the time that has elapsed. 8ucli masses are already 
l)eginning to accumulate, on the surface of the gravels, at the 
bases of the steep mountain slopes adjoining Miiii' iidct. although 
the ice can have retreated from them but a comparatively few 
years ago. Passing down the bay they increase much in size, and 
connect with debris streams lying in tlu' gullies. In the Dirt 
glacier valley the great rapidity of this disintegration is best 
shown. The practically motionless ice occupying this end of the 
valley is covered for its full half mile of width with from two to 
four feet of slaty debris, which increases to a very considerable 
thickness near the sides of the valley. The larger part of this 
debris has fallen from the mountain sides, and in a not xcry great 
space of time. Such dcliris is also found to great extent around 
Pyramid peak. * 
* This is in accord with Mr. 1. C. Russell's observations in southern 
Alaska. Hull. (Jeol. Sue. Am. Vol. I, p. i:?."). 
