756 



Notes and Correspondence. 



[Oct., 



the scooping out of wide, shallow 

 valleys originally formed by faults 

 and small elevation axes. The only 

 exception to this state of things, is 

 when conical hills, detached or 

 grouped, rise up out of the plains 

 and present the curious appearance 

 of mud more or less liquid, welling 

 slowly from an orifice in the ground, 

 forming hillocks by the material 

 erupted, and allowing of a slow 

 escape of certain gases, of which 

 nitrogen and sulphuretted hydrogen 

 seem to be the most frequent. 



In a visit I have recently paid to 

 this part of the world, I have been 

 greatly interested by the mode in 

 which these mud volcanoes are con- 

 nected with petroleum wells, and 

 by the essential difference that seems 

 to exist between the conditions 

 under which petroleum is found in 

 the United States and Canada, and 

 those met with in the East. In the 

 former, as is well known, large quan- 

 tities of oil are tapped, as it were, 

 in the interior of the earth, where 

 stores of this mineral exist under 

 heavy pressure, and where it is 

 kept down by beds of limestone or 

 sandstone more or less nearly hori- 

 zontal. Once tapped, the pressure 

 causes the oil to rise up to, or even 

 far above, the surface, just as water 

 rises in an Artesian well. The pe- 

 troleum obtained in the Crimea dif- 

 fers greatly in the circumstances of 

 getting it, owing to the total differ- 

 ence of the geological conditions 

 of the rocks. In its general nature 

 it is, however, quite similar. The 

 oil is found only at the bottoms of 

 wells, into which it rather oozes 

 than pours from the natural stoi'es 

 in the interior of the earth, what- 

 ever and wherever they may be. 

 The Tatars — the old inhabitants of 

 the Crimea — have sunk innumerable 

 small wells, of which the indications 

 may still be traced, and from the 

 position of these may be obtained 

 an idea of the nature of the sources 

 of supply. The wells thus indicated 

 are almost without exception in 

 narrow bands, extending often, but 

 not always, along the axis of east 



and west valleys, midway between 

 the limestone cappings to the north 

 and south. 



The petroleum springs of the 

 Crimea are entirely confined to the 

 eastern part of that land, and 

 almost entirely to the peninsula 

 of Kertch. There are several very 

 well-marked belts of country in 

 which wells sunk a few yards into 

 the soil yield more or less naphtha 

 of very fair quality, and in most 

 cases these have long been known 

 and worked, though only to a very 

 small extent. During the early part 

 of spring, and also in the early part 

 of summer, the position of the 

 petroleum is considered to be 

 marked by lines of different colour 

 to the rest of the soil. In the 

 eai'ly part of the spring these lines 

 are greener, and in the early sum- 

 mer they are yellower than the 

 rest of the land. This, if it can 

 really be depended on as a useful 

 guide in the discovery of fresh 

 sources of supply, must be due to 

 the influence of the oil on the 

 soil where the naphtha crops out. 

 The whole belt of land containing 

 mineral oil is considerable, reaching 

 across from the sea of Azof to the 

 Black Sea as far as Arabat and 

 Kaffa, and it may extend even 

 farther to the west in the steppes. 

 Beyond Arabat there are, at any 

 rate, numerous springs of petro- 

 leum, as well as of sulphuretted 

 hydrogen, in the Putrid Sea, whose 

 name is derived from the oppressive 

 smell of rotten eggs that pervades 

 the whole atmosphere in this curious 

 expanse of saline water. It is pro- 

 bable that the supply of mineral oil 

 is both very large and very near the 

 surface in many parts of the country 

 where the geological conditions are 

 favourable. 



While examining the most pro- 

 ductive and most remarkable of 

 the naphtha-yielding springs, I was 

 struck with their marked relation 

 to the structure of the rocks, the 

 existence of faults and anticlinal 

 axes, and the numerous and sys- 

 tematic groups of mud volcanoes 



