The soil of this vast depression is entirely argillaceous, and therefore impermeable, so that the waters remain there and make of it a region very difficult to cross during the hot season.

There, however, lies the way to Irkutsk, and it is in the midst of ponds, pools, lakes, and swamps, from which the sun draws poisonous exhalations, that the road winds, and entails upon the traveler the greatest fatigue and danger.
Michael Strogoff spurred his horse into the midst of a grassy prairie, differing greatly from the close-cropped sod of the steppe, where feed the immense Siberian herds.

The grass here was five or six feet in height, and had made room for swamp-plants, to which the dampness of the place, assisted by the heat of summer, had given giant proportions.
These were principally canes and rushes, which formed a tangled network, an impenetrable undergrowth, sprinkled everywhere with a thousand flowers remarkable for the brightness of their color.
Michael Strogoff, galloping amongst this undergrowth of cane, was no longer visible from the swamps which bordered the road.

The tall grass rose above him, and his track was indicated only by the flight of innumerable aquatic birds, which rose from the side of the road and dispersed into the air in screaming flocks.
The way, however, was clearly traceable.

Now it would lie straight between the dense thicket of marsh-plants; again it would follow the winding shores of vast pools, some of which, several versts in length and breadth, deserve the name of lakes.