496 O. H. HERSHEY GEOLOGICAL RECONNAISSANCE IN NICARAGUA 



sandstones and variegated shales, Laramie brown coal, and Cretaceous 

 oolitic rocks and clays, gypsum, salt, and slightly metamorphosed sand- 

 stones. Glacial action is supposed to be indicated by low groups of hills 

 or ridges of unsorted, generally unstratified deposits of clays and sands 

 inclosing numerous stones and pebbles, some smooth and rounded, 

 others angular. Mention is made of a few apparently glacially striated 

 rocks. The Pis-Pis district lies near the eastern edge of this division, 

 but the supposed glacial deposits do not extend into it. 



The third division extends about 250 miles along the eastern coast 

 and about 75 miles inland. No mention is made of the bedrock series. 

 It is contended that this part of the coast has subsided until recently at 

 a rate equal to that of the sedimentation over the delta of the rivers 

 Escondido, Matagalpa, Tungla, Wanta, Segoria, and of several smaller 

 streams. He thinks that during the supposed Glacial epoch in Nica- 

 ragua the land extended more than 1,500 miles farther east than at 

 present, and that the eastern coast ceased to subside a few years ago and 

 is now being slowly elevated, giving as evidences of the latter that the 

 corals that grew nearly into the mouths of the rivers now are dead at the 

 tops of their branches, due to the sediment -loaded river waters extend- 

 ing farther seaward than formerly; also that the atolls and barrier reefs 

 off the coast have the peaks of their coral formations exposed and dead 

 above all ordinary tides and storm waves. He also describes two river 

 systems in the country immediately west of the delta region, one includ- 

 ing the dry beds of ancient rivers and the other the present river chan- 

 nels. The former are from 100 to 500 or more yards wide and traceable 

 for many miles. 



In 1893 Crawford described* "granite outbursts" exposed on the tops 

 of oval-shaped cerros, and also occurring in two parallel lines of spurs 

 and ridges that extend northeastwardly for about 90 miles from the 

 Barbar Mountains to near the confluence of the Eios Wasspuc and 

 AVanque ("Wanks). He also describes so-called moutonned ridges as 

 evidence of glaciation over several thousand square miles. They extend 

 in a series of parallel oblong ridges 60 miles northeastward from near 

 the base of the tall Barbar and Pena Blanca Mountains, the altitude of 

 which is over 7,000 feet above the sea. One of the "moraines" extends 

 farther northward, is 90 miles long, and terminates at a dike on the 

 sides of which are auriferous gravels, in which the Rio Wanque has cut 

 its channel at San Eamon. The "moutonned ridge" country has a width 

 of 25 miles from east to west and the rido^es rise 70 to 1:00 feet above 



* Recent discoveries in northeastern Nicaragua, etcetera. Science, vol. xxii, 1893, po. 

 269-272. 



