BOOK FOR GOLD-SEEKERS.             248
"Since the formation of the veins and other deposits of
the rocks of the gold belt an enormous length of time has elapsed. During that time the forces of erosion have stripped off the overlying rocks and exposed the metalliferous veins at the surface for long periods, and the rocks of the gold belt, with the veins which they include, have crumbled and been carried away by the streams, to be deposited in widely different places as gravels; or sands, or mud.   In Alaska the streams have been carrying away the gold from the metalliferous belt for a very long period, so that particles of the precious metal are found in nearly all parts of the territory.
"It is only in the immediate vicinity of the gold-bearing belt, however, that the particles of gold are large and plentiful enough to repay working under present conditions. Where a stream heads in the gold belt the richest diggings are likely to be near its extreme upper part. In this upper part the current is so swift that the lighter material and the finer gold are carried away, leaving in
-many places a rich deposit of coarse gold overlaid by coarse gravel, the pebbles being so large as to hinder rapid transportation by water.
"It is under such conditions that the diggings which are now being worked are found, with some unimportant exceptions. The rich gulches of the Forty Mile district and of the Birch creek district, as well as other fields of less importance, all head in the gold-bearing formation.
"A short distance below the heads of these gulches the stream valley broadens and the gravels contain finer gold, more widely distributed. Along certain parts of the stream this finer gold is concentrated by favorable currents, and is often profitably washed, this kind of deposit   coming under the head of 'bar diggings.' The gold in these more extensive gravels is often present in sufficient
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