568 PROCEEDINGS OF THE GEOLOGICAL SOCIETT. [JunO 20, 



of Pichincha. In this latter locality, and in beds of more recent 

 date than those which extend to the coast, roots and stems of small 

 trees, completely carbonized, have been found, some descending to the 

 depth of 100 feet below the surface. Whilst the trees in this latter 

 locality, though of more recent production, are converted into perfect 

 charcoal, those of the older volcanic deposits are not at all carbon- 

 ized. And, again, the wood of the buried forest at the mouth of the 

 Esmeraldas, lying only 12 to 15 feet under beds of an estuarine clay, 

 and much more recent than either of the above, is partially carbon- 

 ized, and resembles lignite. It is the author's opinion, in regard to 

 the charred wood in the vicinity of Pichincha, that, as the ashes 

 and dust throvni out by that volcano fell in dense showers over 

 the surrounding country, the heat still retained by this matter car- 

 bonized the trees which it enveloped and buried. 



It is beneath this volcanic deposit, or in some of its lowest beds, 

 that the gold-drifts are found, as at Playa de Oro, Cachibi, at Bar- 

 bacous, New Granada, &c. And it is only when this deposit has 

 been removed, or where ancient river- courses have been again pene- 

 trated by waters of more recent times, that gold is found in this part 

 of Ecuador and the adjoining part of New Granada. 



The projected volcanic matter is distributed in terraces, the most 

 recent of which extends along the shores of the Esmeraldas, and is 

 but slightly above high-water mark. The second rises in some places 

 10 feet above the former, and is extensive at the lower part of the 

 Esmeraldas and up the valleys of its lower tributaries. A third, 

 presenting a distinct margin, rises about 8 feet higher ; and above 

 this rise three other terraces, respectively, in their orders of ascent, 

 15, 12, and 6 feet. This is the arrangement which (with the ex- 

 ception of the lowest and therefore the most recent terrace) is clearly 

 defined in ascending the north side of the river Esmeraldas from oppo- 

 site the river Viche to the Quebrada of Chancama (see section). At the 

 former place the terraces recede from the river to an undetermined 

 distance, but which is evidently extensive, and are said to reach to the 

 Rio Yerde, which receives a portion of the drainage from them : this 

 seems the more probable, as but an inconsiderable amount of the 

 water falls into the Esmeraldas. The series of terraces is again 

 met with in the road above the mouth of the river Sadi, their con- 

 tinuation being partially broken by the projection of a range of hiUs. 

 It is observable in this locality that the river has cut its way deep 

 across the terraces, and in many places completely through the vol- 

 canic matter, and regained its more ancient bed on the Carboniferous 

 rocks. 



Rocks of Tertiary age are represented in the limestone cliffs, 

 resting on shale, north of the Rio Yerde, and at the side of the river 

 Esmeraldas, just above the old town of that name, where the lime- 

 stone is overlain with the volcanic deposits. Again, the Tertiary 

 limestone was found much further up, where the river passes through 

 a range of hills in the vicinity of the river Caninde ; here it appears 

 by the river-side in enormous white angular blocks, which had 

 evidently fallen from the side of the precipitous hill behind: the 



