In 1935 the author was making geological explorations in the upper course of the Zeravshan River which flows through the territory of the Tadjik SSR. During these works he was able to visit the outcrops of alkaline rocks in the region of the upper waters of the river Tagoba-Sobak (fig. 1). The coordinates of the outcrop of the alkaline rocks are as follows: Longitude 69° 40′ E (from Greenwich), latitude, 39° 45′ N. The alkaline rocks of the outcrop in question had been visited previously by several explorers, and they are described with sufficient details in a paper by M. A. Preobrajensky, published in 1911 (8). Yet the field observations of the author of the present paper and the microscopic examination of thin sections of the rocks collected suggest somewhat different ideas concerning the genesis of the alkaline rocks of Tagoba-Sobak in contradiction to the data published in special literature. This circumstance induced the author to put the materials in his possession to a more detailed study the conclusions whereof are briefly set forth below.

Random samples of thin sections of molten rocks, which were given to us by A. V. Vvedenskii, were studied. We did not aim at a systematic study of this random, though rather extensive (about 200 thin sections) material, and in this note we limited ourselves to only some data characterizing the more common types of these "artificial rocks". The vast majority of the studied thin sections are glasses that have just begun to recrystallize with the formation of spherulites or various kinds of skeletal formations. Only in a few thin sections could one find minerals individualized in such a form that they were amenable to optical examination. Therefore, the main task of the study was the study of structures, and a considerably smaller amount of work involved the study of minerals.