58 Tlic American Geologist. Ji'i.v, i898 
The writer has none but improvised seismic instruments, improved 
on as used for several years, and but few of them were in good working 
condition when. the first severe seismic disturbance in this series passed. 
The direction of the waves was northwardly and southwardly, and 
the rapidity of their movement was about as herein stated. 
Managua, Nicaragua, May igth, i8q8. J. Crawford. 
The St. Croix River Valley. In the descriptions of the St. 
Croix river valley brief references have been made to the preglacial and 
postglacial courses of the river. The definite relation of these courses 
has not been determined. Mr. Warren Upham states, that the occui- 
rence of the Upper and Lower Dalles of the St. Croix strongly sug 
gests that there, and along some contiguous extent of the present 
valley, the stream is now flowing in a course which it has cut during 
and since the Ice age. No closely adjacent belt, however, seems to 
l)e probably identifiable, as a drift filled preglacial valley. In pre- 
glacial times the St. Croix river was" represented by two quite inde- 
pendent rivers, each tributary to the Mississippi. The greater part 
of the St. Croix drainage basin including all above Taylor's Falls 
flowed south and southwestward from the mouth of the Sunrise river 
to a junction with the Mississippi somewhere between Anoka and Min- 
neapolis. * * * * About a sixth part of the St. Croix basin lying 
east and south of Taylor's Falls appears to have been drained by a 
stream coinciding nearly with the Apple river and the lower thirty 
miles of the St. Croix river.* 
The recent observations of Dr. C. P. Berkey, in the vicinity of the 
Dalles, also indicate the postglacial character of that part of the gorge. t 
The St. Croix valley varies from one-half to one mile in width and 
is i68 miles long. Based upon the various physiographic features, the 
valley presents three sharply defined parts designated in this paper the 
Upper, Middle and Lower St. Croix. 
The Upper St. Croix. Beginning at the Upper St. Croix lake the 
course of the St. Croix valley extends in a southwesterly direction for 
90 miles, to the northeast corner of Chisago county in Minnesota. 
Thence it extends nearly south for ten miles to the Big bend at the 
mouth of the Sunrise river. In this distance of 100 miles the river 
descends 310 feet. The valley has an average depth of about 100 feet. 
From the abundant undisturbed glacial drift below the top of the early 
rock gorge it is evident that the valley is essentially of preglacial 
origin. During postglacial time the river has cut through the drift 
in many places and is now cutting its way below the preglacial surface. 
The tributaries to the Upper St. Croix show the same relations between 
the preglacial and postglacial erosion. In the vicinity of Sandstone, 
Minnesota, the Kettle river flows in a preglacial gorge from 100 to 150 
*Thf' St. Croix liver before, durinpr, and after the Ice ago, p. 48, by Warren Up- 
ham. Eoport of the Commissioner of the State Park of the Dalles, 1896. pp. 45-58. 
tGeology of the St. Croix Dalles, p. 367. Amer. Geol., vol. XX, Dec. 1897. 
