1897.] NEW YORK ACADEMY OF SCIENCES. 167 



lying swamps and vallej^s evidently of Tertiary origin separa- 

 ting these two. (See PI. XV.) Within a comparatively short dis- 

 tance, there are three distinct geological systems each non-conform- 

 able to the otlier, yet all in place very nearly as originally formed. 



My mission was to investigate certain coal deposits found in 

 the valleys, and claimed to be of true Carboniferous age, of the 

 best quality and to be had in the greatest abundance. The 

 work of exploration began at Rio Hacha, to the eastward of the 

 Sierra Nevada mountains, a little seaport lying near the mouth 

 of the Rio Rancheria. Here I found a broad flat country all 

 sand and bush underlain b}' deposits of hard marls apparently of 

 Miocene age. These prevented any vigorous growth of trees for 

 a number of miles back from the sea and the country had a bar- 

 ren and rather dreary appearance. 



After a short delay a start was made for the coal fields, a three 

 days' journey, the route taking- us across the sand deposits and 

 through low wet places to the base of the eastern terminus of 

 the Sierra Nevadas ; then around this point and into a hot low 

 lying valley. Here we followed the course of the Rio Rancheria 

 to a point opposite a prominent peak in the eastern Andean ex- 

 tensions called the Cerrajon mountain. The valley was about 

 twelve miles wide between the foothills of the Andes mountains 

 on the east, and those of the Sierra Nevadas on the west. At 

 some places it seemed as if this valley was almost at sea level. 



The surface of the country appeared to be a recent alluvium 

 marking old water courses, and the general upper strata seemed 

 to be of well packed clay, shale-like at some places, with here 

 and there surfaces of red iron bearing shales in thin strata, ap- 

 parently a recent residue conformable to the irregularities of the 

 underlying material ; and scattered over the surface there were 

 well worn boulders and gravels of Cietaceous limestone rich in 

 fossils. This looked like a very recent formation, and I had 

 seen fossils on the way up that had every appearance of being 

 in place and of Miocene origin. I was deeply interested in the 

 strange surroundiuirs, but my faith in extensive coal deposits 

 was a little shaken, although tlie remembrance of glowing reports 

 made by others who had examined the country, and whose 

 names I shall not quote out of deference to their opinions, soon 

 restored my confidence. 



The following day as early as possible I was on my way to 

 look at the immense coal fields. The first showing was a disap- 

 pointment, only a mass of soft decom[)Osed material exposed be- 

 tween clay-like shales at a break in the surface, probably caused 

 by the crowding and intrusion of ridges just beyond, or possibly 

 by an uplifting of the whole mountain mass some two miles 



