Glacial Lakes and Rivers in Swede?!. — Upham. 235 
they are a good incentive for more detailed explorations, with 
sufficient determinations of altitudes by levelling. 
It would be highly interesting if the rate of final recession 
of the ice-sheets of North America and Europe upon any parts 
of their areas can be ascertained. The most definite testimony 
given on this question by drift deposits in any locality known 
to me was pointed out by Baron Gerard De Geer in a short 
excursion on which he guided me to a series of morainekts, if 
this term may be used, situated on a tract about three miles 
long from east to west and one to two miles wide, lying next 
west of the little railway station of Sundbyberg, which is three 
miles northwest of Stockholm. Each morainelet there is from 
5 to 15 rods wide, and from 5 to 25 feet high above the adjoin- 
ing surface, which consists of level cultivated fields of marine 
clay, excepting frequent exposures of the granitic bedrocks, 
moutonneed, which are bare on considerable spaces, having 
no drift nor boulders, strongly in contrast with the drift knolls 
and small ridges of the morainelets, encumbered with their 
abundant boulders up to 10 feet or sometimes 20 feet in 
diameter. These little moraines, approximately parallel and 
traceable more or less continuously from east to west, occur 
to the number of eight or ten on the width of about a mile. 
If they represent successive years of the glacial retreat, as De 
Geer thinks, it had there a rate of about a hundred miles in a 
thousand years, which would agree in a general way with the 
duration of the Champlain or closing epoch of the Ice age as 
estimated from other lines of investigation on both these conti- 
nents. 
One of the special inquiries which Baron De Geer is now 
prosecuting relates to the possible correlation of the intervals 
between these morainelets with the probably annual layers of 
clay deposition attendant on the withdrawal of the ice-sheet, 
observed at many places in southern Sweden nearlv as at 
Chaska, Carver, and Jordan, in the Minnesota river valley. 
With these apparently annual glacial records, he also thinks 
that an additional correlation may be afforded bv the succes- 
sive knolls, widening, or changes in coarseness of material, 
which many eskers display at short intervals of their course. 
