MARCH 22, 1901.] 
CURRENT NOTES ON PHYSIOGRAPHY. 
PHYSIOGRAPHY OF NEW BRUNSWICK. 
GANONG continues his ‘ Notes on the Natural 
History and Physiography of New Brunswick’ 
(Bull. Nat. Hist. Soc. New Brunswick, xix, 
1901, 313-840), presenting accounts of the de- 
velopment of several rivers and lakes. The 
Nepisiguit, for example, is explained as the 
result of successive captures of portions of 
three other systems by what is now the lower 
part of this river. The Negoot lakes, of 
picturesque outline in a district of primeval 
forest, are described as resulting from the 
obstruction of a series of nearly parallel val- 
leys by masses of glacial drift. In the dis- 
cussion of these problems it is implied that 
the shores of the Silurian sea are indicated 
by the present margin of the Silurian strata, 
that certain existing river courses were deter- 
mined in pre-Silurian times and that even the 
valleys of certain rivers and lakes are pre- 
Silurian; but it is difficult to accept these 
conclusions on the evidence that is presented. 
A slight misapprehension as to the meaning of 
‘monadnock’ is indicated in the statement that 
a hill which rises over the eastern] peneplain 
of Carboniferous strata east of Grand lake is 
‘not a real monadnock,’ for ‘it is composed of 
a ridge of volcanic rocks, and hence remains, 
not because it is left behind in the general 
erosion, but because it resists erosion better 
than the surrounding rock.’ It is for such 
resistant residual mountains and hills that 
the term monadnock is coming to be generally 
used. 
DRAINAGE CHANGES IN NORWAY. 
‘THE Sundal Drainage System in central 
Norway,’ by R. L. Barrett (Bull. Amer. Geogr. 
Soc., xxxii, 1900, 199-219), is an account of a 
curious series of changes in drainage lines, 
whereby the upper valleys of the Opdal system 
that once discharged northeastward into Trond- 
hjem fiord are now discharged northwestward 
to Sundal fiord. The Opdal system consisted of 
numerous broadly open valleys with convergent 
courses and continuously sloping floors. The 
Sundal, a canyon like valley, trenches the high- 
lands in which the upper Opdal branches are 
SCIENCE. 
471 
opened, and receives the waters of several nar- 
row gorges that are eroded in the mature Opda] 
floors. As a result the lateral stream courses 
to-day no longer converge towards their trunk, 
but enter it ina backhanded or barbed fashion ; 
Sundal system, solid black. Opdal system, outline. 
and while the heads of the Opdal system were 
well enclosed by the highlands, the head of the 
Sundal system is separated from the head of 
what remains of the Opdal system only by a 
flat divide on the mature valley floor. As the 
gorges and canyons of the Sundal system 
deepen downstream through the rising valley 
floors of the dismembered Opdal system, the 
main Sundal canyon comes to be 1,000 meters 
deeper than the highest head valleys that it 
dissects. In explanation of these curious 
changes, Barrett concludes that normal head 
ward erosion by the Sundal system is of uncer- 
tain and probably small value ; westward over- 
flow from ice-dammed lakes that occupied the 
upper Opdal valleys while the trunk was filled 
by advancing or retreating glaciers is given 
more importance; and a still greater share of 
work is attributed to glacial overflows, when 
great ice-sheets overwhelmed the region and 
disregarded the divides that had controlled 
preglacial river drainage. It is pointed out 
that the Romsdal, next southwest of the Sundal, 
exhibits a similar barbed relation between its 
branch and trunk streams, thus suggesting an 
interesting field of study for a summer month in 
Norway. 
THE ASSAM EARTHQUAKE OF 1897. 
A THOROUGH ‘ Report on the Great [Assam] 
Harthquake of 12th of June, 1897,’ has been 
made by R. D. Oldham (Mem. Geol. Surv., India, 
KXIX., 1899. Pp. xxx + 379+ xviii., 41 pl., 
3 maps). This earthquake is said not to have 
