Ch. XII.] 
TERTIARY STRATA AT NICE, 
1G9 
ties nearer to Nice. From these fossils it clearly appears that 
the formation belongs to the older Pliocene era. 
Such alternations of gravel and the usual thin layers of fine 
sediment may easily be explained, if we reflect that the rivers 
now flowing from the Maritime Alps are nearly dried up in 
summer, and have only strength to drift along fine mud to the 
sea ; whereas, in winter, or on the melting of the snow, they 
roll along large quantities of pebbles. The thicker masses of 
loam, such as that of St. Madeleine, may have been produced 
during a longer interval, when the river shifted for a time the 
direction of its principal channel of discharge, so that nothing 
but fine mud was for a series of years conveyed to that point in 
the bed of the sea opposite the delta. 
Uniform and continuous as the strata appear, on a general 
view, in the ravine of the Magnan, we discover, if we attempt 
to trace any one of them for some distance, that they thin out 
and are wedge-shaped. We believe that they were thrown 
down originally upon a steep slanting bank or talus, which 
advanced gradually from the base of Monte Calvo to the sea. 
The distance between these points is, as we have before men- 
tioned, about nine miles, so that the accumulation of superim- 
posed strata would be a great many miles in thickness, if they 
were placed horizontally upon one another. The strata nearest 
, to Monte Calvo, which may be expressed by a, are certainly 
older than those at b, and the group 6 was formed before c. 
1 The aggregate thickness, in any one place, cannot be proved 
to amount to 1000 feet, although it may, perhaps, be much 
greater. But it may never exceed three or four thousand 
feet ; whereas, if we did not suppose that the beds were origi- 
nally deposited in an inclined position, we should be forced to 
imagine that a sea, many miles in depth, had been filled up by 
horizontal strata of pebbles thrown down one upon another. 
At no great distance on this coast the Var is annually seen 
to sweep down into the sea a large quantity of gravel, which 
1 may be spread out by the waves and currents over a consider- 
able space. The sea at the mouth of this river is now shallow, 
