166 EXPLORATIONS IN TURKESTAN.
COMPARISON WITH AMERICAN FORMATIONS.
Before leaving the Mesozoic-Tertiary series there is another phase of the subject which deserves mention, because of its bearing on the world-relations of the continents. The existing physiographic features of this portion of Asia bear, as has been suggested, a certain resemblance to those of the southwestern portion of the United States, the so-called Basin Range and Plateau provinces. If the rock series and the geological events of the one country be compared with those of the other it is seen that while there is considerable difference in details, there is also a significant resemblance ; hence the fundamental fcatures of the past, as well as of the present, are similar. This is set forth in Table II, where American features which are the same as those of Asia are marked Do." It is not meant to imply that the two series of features were identical in time, but merely in sequence. The similarity seems too great to be accidental ; it may be that we have here the normal sequence for an interior desert basin. If this is so we ought to find the saine general rock series in other desert regions, such as Arabia and parts of the Sahara, where similar conditions prevail.
TABLE II.—Comparison table of the Mesozoic-Tertiary rock series and of geological
events in the elevated arid regions of Asia and North America.
Paleozoic moraine deposition.
Mountain-making and prolonged Shales
Estuarine or playa deposition.
Conglomerate a n d sandstone.
Subaerialdeposition. Land slowly sinking or stationary.
Clay shales and coal measures.
Estuarine or swamp conditions...
Vermilion sandstone. cross-bedded.
Elevation and possibly desert conditions.
Depression and return to moraine conditions.
White cross-bedded sandstone.
More rigorous desert conditions.
Unstable marine conditions
Cretaceous coal measures.
Estuarine or swamp conditions.
Elevation and eventually a gradual return to subaerial conditions of depositions
Brown sandstone and conglomerate.
Complete return to subaerial deposition.