74 The American Geologist. August, i899 
thick cap-rock or original covering. However, it is beyond 
question that the entire width of the range on this Hne is made 
up of igneous rocks of a deep-cooling rather than a "surface 
volcanic" nature. They constitute the "Veraguas formation" 
which, from its relation to other geologic features of the isth- 
mus country, I consider of early Tertiary age, probably 
Eocene; certainly not so old as the Cretaceous period. 
The diabase and syenyte of the Veraguas formation extend 
beyond the mountains on the north to form the caiioned, sea- 
ward sloping, piedmont belt. It is at and in the near vicinity 
of the junction between the sierras and this dissected plain that 
is situated the northern or Veraguas gold-belt, extending along 
the edge of the mountain country for a distance of perhaps 150 
miles, yet probably averaging in width no more than two or 
three miles. It is the richest on the isthmus, but owing to the 
dense, jungle-like vegetation, and the daily rains is not now- 
mined. All the streams, issuing from the mountains and cross- 
ing the quartz belt, are rich in placer gold, and some were 
mined for hundreds of years, by the Spaniards and Indians. 
From the universal forest covering, the quartz veins are dilB- 
cult to find, and not many have yet been uncovered. Those 
examined by me were chiefly on the headwaters of the Rio 
Santiago. They were fissure veins, generally about vertical, 
and varying in width from several inches to two feet. The gold 
bearing quartz is white and the gold is free. Associated with 
these white veins, are thin stringers of heavy iron and manga- 
nese sulphurets. Curiously, these pyritous ores are nearly bar- 
ren of gold. None of the veins observed were connected with 
detectable faults or contacts. 
The important points to which attention is to be drawn 
are, that the mineral belt passes indiscriminately across the 
areas of the diabase and syenyte, and that similar quartz veins 
occur in the same formations on both sides of the gold-belt and 
yet are practically barren. If the gold has been derived from 
the enclosing formations, why is it not abundant throughout 
the areas of these formations, particularly in the interior of the 
Cordilleran region? 
The southern or Remanse gold-belt has been traced, and 
hundreds of veins located, between the villages of San Fran- 
cisco and Cafiazas, a distance of about twenty-five miles. It 
