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196 F A L L O F M O N T G R E N I E R .
plain, which extends to the valley of the
Isere. It is several miles in length, and
is connected with the mountains of the
Grand Chartreux; but it is very narrow.
Its longitudinal direction is from east to
west: near the middle it makes a bend
towards the north, forming a kind of bay
or concavity on the southern side; and
there is a corresponding convexity or projection
on the northern side. It has been
generally believed, that the part of the
mountain which fell down was from the
middle, and that the eboulement formed
the concavity on the southern side; but
this opinion appears to me erroneous, as
the direction of the ruins, and the form of
the mountain, indicate that it was the
south-eastern side which fell.
Mont Grenier rises very abruptly upwards
of 4000 feet above the plain. Like
the mountains of les Echelles, with which
it is connected, it is capped with an immense
mass of limestone strata, not less
than 600 feet in thickness, which presents,
on every side, the appearance of a wall.
The strata dip gently to the side which
fell into the plain. This mass of limestone
rests on a foundation of softer strata, prc-
bably molasse; but I could only examine it
1^1