Neolithic Mail in yinir(i(/n<i. — i'rdirfnrd. IfiS 
they are too tlioroughl}- sorted or separated according to their 
densities to be ashes iminediateh' from volcanoes falling on the 
hardening stratum of rock. 
The strata of hardened volcanic conglomerate ejecta were de- 
posited, each stratum most prol)al)ly from large deep floods of 
mud brought down in continuous flow during one season, bv tor- 
rents after long continued heavy rains, from the adjacent monte- 
cules, cones and cerros of materials erupted from volcanoes. 
The superficial deposit ( four to twelve feet deep, uncompacted ) 
was formed by several small floods of mud. occuring at intervals 
of several years. That these floods of mud occurred and that 
thej' were so thick in this locality is confirmed l)y vivid descrip- 
tions by some of the most eminent, educated and reliable citizens 
in Nicaragua who describe a similar occurrence on Octol>er 4. 
187G. In this locality the city of Managua, the local name of 
these torrential floods of mud is '• aluvions de barro; " this alu- 
vion de barro filled the open houses, streets and plazas near the 
lake five and one-half feet deep with thick mushy mud composed 
of materials similar to those that are formed into hard conglom- 
erate, hereinbefore described. Much of the slowly moving mud 
which remained in the city was washed into the lake by subse- 
quent rains, but large masses were left in protected places, which 
have dried and hardened into isolated areas about twent3'-four 
inches thick. Some of its upper surface, probabh' was washed 
away Vn' rains because when these isolated parts, now hard and 
24 inches thick, were prevented from flowing further, they were 
fully five and one-half feet deep, slowly flowing masses of thick 
mud. Several large boulders, some of them fully twelve tons in 
weight, were moved from depressions or concavities on the 
mountain's side. al)Out one mile to the south of the city, where 
they had hardened. They were not hard enough to have l)een 
rolled even for 100 yards without breaking into fragments, but 
were deposited in the streets of Managua. A canal that once 
extended for two miles from east to west, and was fort}' feet wide 
and ten feet deep, was filled up by the nuid flood, October 4. 
1870, and is now one of the principal thoroughfares for traffic. 
At this date natural forces were acting on a grand scale, in this 
locality, changing the position of large (luantities of material, 
yet the forces were small in comparison with that enormous flood 
of mud, which transported from the adjacent monticules and 
