GLACIATION IN GHEE CALLIN DISPRIGIne DD klgsiSir 
COLUMBIA. 
In the Atlin district of Northern British Columbia the topog- 
raphy east of the coast range is characterized by wide main 
valleys having a general elevation of a little over 2,000 feet 
above sea level; between these main valleys are groups of 
mountains separated by other wide but more elevated and 
sloping valleys. 
Both of these valley systems show evidence of glacial action 
but both also appear to have been deep drainage channels before 
the advent of this glacial action, and, to have received since that 
period no great modification in their form. 
The upper system of valleys, broad, flat and inclined at a 
moderate grade, look too big for the comparatively small and 
rapid streams which drain them. These streams moreover have 
only cut narrow gutters to no great depth below the general 
floor of these valleys. 
In this district there is evidence of two glacial periods, a 
regional glaciation, and a local glaciation, in part, over the same 
ground, at a later time. There is also a present active and 
extensive local glaciation now going on in the coast ranges to 
the westward. The latter may be a survivor or remnant under 
more favorable conditions of the two former periods. 
The earliest regional or Cordilleran glacier left its evidence 
upon the main valley floors, and upon the upper slopes of 
the highest mountain groups in the district, a difference of 
about 5,000 feet in altitude. The movement was in a northerly 
direction. 
The later local glaciation may have been due to the action 
of a remnant of the regional glacier, but appears more likely to 
have been the result of a later dispersion from a local névé. This 
glaciation followed these upper valleys and slopes, leaving the 
upper mountain groups above their action. 
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