396 The American Geologist. Decomber, 1902. 
so as to afterwards (unto the date of this letter) prevent the naviga- 
tion of that river by vessels of size sufficient to transport cargoes be- 
tween Cadiz, Spain, and Granada, at the west margin of lake Nicaragua, 
also between Cuba aind Granada. Nicaragua: Ayon's "History of 
Nicaragua" — (the only reliaible history of the country published) tells,. 
Vol. 2, chap, vi, pp. 6465, of a "ship that was in the lake Nicaragua 
during the several earthquakes of 1663, that had come loaded with 
merchandize from Cuba ; that after the earthquakes and rise of the bed 
of San Juan river, Pjcar its exit from lake Nicaragua, never succeeded 
in getting out of the lake — altho endeavoring to do so several times." 
It is probable that transportation of ships across Nicaragua would 
have ceased — for a month or so — until the elevation of about one- 
fourth of the length of the bed of the Rio San Juan had been dredged 
to a proper or to its former depths. No fissures are to be four.d in, 
across, or near that river. j. Crawford. 
^VORK OF THE CORNELL SuMMER ScHOOL OF FlELD GeOLOGY. Dur- 
ing the four past summer seasons, Prof. G. D. Harris of Cornell 
University has conducted a series of geological expeditions which 
have been very beneficial to the students who have taken the work 
and also been the means of adding not a little to the accurate knowl- 
edge of New York stratigraphy. 
Thoroughly believing in field work for beginners as well as for 
advanced students, professor Harris owns and keeps in repair two 
gasoline launches that the best service possible may be given to the 
expeditions. By this means the party has (i) access to all the var- 
ious water-ways of the state, (2) means for transporting camp mater- 
ials, fossils, &c., and (3) a means of travel free of charge. 
Two classes of students have availed themselves of the oppor- 
tunities, viz., beginners in geology who wish to see the country and 
learn how detailed work is done, and those more advanced, graduate 
students, instructors, &c., who .have wished to apply themselves to 
some particular problem and work it to completion. For the latter 
class all the machinery of the department is at hand. Camp is 
pitched to stay till the field work on such particular problems is done. 
The beginners are given tramps over the region until they are fa- 
miliar -with the topography, and then they are asked to help in the 
detailed work. If this program seems unfair to the beginning class, 
it is only necessary to state that the beginners of one season become 
the producers of the next. 
The first trip was in 1899. Professor Harris took five men in one 
of his launches on a four week's trip through the different water- 
ways of the state. In igoo permanent camp was pitched at Trenton 
Falls and side trips were taken to lake Champlain and through the 
Mohawk valley via the Erie canal. It was during this season that 
a new fauna was fouind in the Calciferous of the Mohawk valley. 
Dr. H. F. Cleland, now professor of geology at Williams, described 
this new fauna in Bulletin No. 13 of "Bulletins of American Pal- 
eontology". A topographic map of the region was made by Mr. A. 
