Reviews—A lex. Ivchenko on Afolian Deposits. 523 
of stratification in eolian deposits can be divided into ‘ barkhans’,' 
ripple-mark, diagonal with opposed dips, discordant parallelism with 
great differences in the dips, horizontal and vertical. These types 
occur both in sandy and dusty accumulations. One can observe in 
purely zolian deposits, strata due to insulation (limy, saline, or irony), 
to vegetation (earthy, clayey), or to wind; and these can be further 
subdivided. One can trace certain characteristics as one passes from 
the desert type of deposits to that of the edge of the desert and from 
that to the steppe. The loess of Turkestan is purely eolian, while 
that of Kiev is aquatic. Similarly, one can judge how different beds 
of other geological ages were formed; thus the red grits of Tartarian 
age were xolian, while the sands bordering the Dnieper were aquatic. 
It is necessary to distinguish the dusts of deserts formed from the 
denudation of local rocks from that formed from the denudation of 
the soils in depressions. In addition to ordinary winds the -action 
of whirlwinds can often be distinguished by the spiral or circular 
arrangement of the dust particles. Whirlwinds, too, have a certain 
influence in the formation of desert depressions. Gentle breezes 
blowing towards ridges do not seem to have much influence in elevating 
dust unless the escarpment is below 30. Erosion and denudation of 
accumulations of dust upon low slopes seem to be localized and do not 
have a general influence. ‘he dimensions of particles of desert dust 
transported by the wind diminish from the centre towards the margins 
of the desert: the dimensions of the dust of the soil, which are less 
mobile and less carried, diminish from the margins to the centre. The 
erains of sand have special characters in eolian and in aquatic deposits ; 
in the former they are characteristically triangular. The vertical 
separation of accumulations of dust or sand can, up to a certain point, 
be attributed to the existence of vertical stratification. Similar beds 
due to the resistance of wind pressure may be in part the result of 
pressure of the upper beds on the lower beds of such deposits. The 
first (due to resistance to the pressure of the wind) form the surface 
of the accumulation, and the second (due to compression) form the 
interior. 
T11.—Brier Notices. 
1. ‘‘ Les Cavernes ET LES RIVI=RES SOUTERRAINES DE LA BELGIQuE”’ 
is the title of a sumptuously illustrated work by E. van den Broeck, 
E. A. Martel, and K. Rahir, which has been published at Brussels in 
two volumes, 1910, illustrated by 26 plates and 435 text-figures. 
There is a total of 1857 pages, arranged in an extraordinary manner, 
as there are sundry interpolations independently paged in successive 
places in each volume, so that precise reference is rendered difficult. 
The subject is dealt with in special relation to the hydrology of the 
Devonian and Carboniferous Limestones, and the question of potable 
waters. 
The great purity of the Givetian Limestone in, the Devonian and of 
the Upper Visean Limestone in the Carboniferous has facilitated the 
corrosive action of water and led to the production of some of the more 
1 Semicircular continental dunes. 
