138 
IOWA ACADEMY OF SCIENCES. 
of steep-sided hills, or mountains, each isolated from the 
others. The principal town of the region is Piatigorsk, 
which is about ten miles from the railway station of Mine- 
rain iy a Vody. 
The purpose of referring at this time, to these hills, which 
reach elevations from 1,500 to 2,500 feet above the plain 
(figure 5), is to call attention to certain geological phe- 
nomena that are unusually well developed; and incidentally 
to exhibit photographs of the highest mountain peak in 
Europe, which is nearby. 
The plain around Piatigorsk is made up of flat-lying 
Tertiary deposits. Out of these rise the isolated volcanic 
mountains, composed mainly of white or gray trachytes. 
The ash and scoriaceous materials have all been removed, 
leaving the harder lavas which occupied the pipes of the 
vents and the central parts of the cones, standing out in 
abrupt mounds. These vents appear to represent the 
dying stages of the great outburst which gave birth to the 
towering volcanic cone of Mt. Elburz, twenty miles distant. 
Authorities have long considered Mt. Blanc, in the Alps, 
to be the highest point in all Europe. Its height above 
sea-level is placed at 15,780 feet. Recent measurements 
show that the Caucasus mountains present no less than 
five peaks, every one of which is more elevated than any 
part of the Swiss district. 
Mt. Elburz is an isolated cone on the north flank of the 
great Caucasian chain, and rises to a height of 18,526 feet 
