ally level
platform. But above the hard limestone are successive layers of a far
different character--layers of sand, of Beauchamp sandstone, mingled
with marl, making a moist, impermeable, infertile soil; then another
layer of limestone, softer and more clayey than that below. Finally,
this upper limestone is covered, especially toward the east, with thin
layers of marl, clay and, lastly, Fontainebleau sand, which are
connected with the strata of the Tardenois. Thus, to a depth of 100
metres, we find a succession of diversified strata, hard and soft, dry
and moist, which impart great variety to the landscape.

The valleys which intersect this conglomeration run from east to west,
toward the deep depression hollowed out by the Savieres and the Lower
Ourcq. From north to south, we can count three--the Upper Ourcq, by
Fere-en-Tardenois and La Ferte Milon, the Ru d'Alland, and the Clignon.
Very wide where they pass through the upper strata, these valleys grow
abruptly narrower and deeper when they reach the level of the hard
limestone, where they are little more than deep and narrow ditches.
Between these furrows, the marl, sand, and softer limestones form
ridges, now steep, now rising more gently, the sandy soil bearing woods,
the limestones cultivated fields.

[Sidenote: The ridges run east and west.]

Thus the whole plateau of the Orxois is a series of elevations and
depressions, running from east to west, which form just so many
obstacles to an advance from south to north like that of the Allies.
Luckily they approached this locality at the same time from the west,
which enabled them to outflank the obstacles simultaneously with their
approach from the south.

[Sidenote: Torcy, Belleau and Bouresches.]

North of Chateau-Thierry, three or four kilometres from the Marne, the
plateau is less diversified. The only obstacle is the valley of the
Clignon, which deepens rapidly toward the west. Above it, at the summit
of the limestone cliff, the plateau forms a species of promontories on
which are built villages--Torcy, Belleau, Bouresches. The American
troops had held their positions there during the last part of June, and
it was there that the heroic marines halted the enemy in his march upon
Paris. And again, it was there that they assumed the offensive on July
18, to outflank Chateau-Thierry from the north. On that day they carried
the ridges of Torcy and Belleau; on the 19th they pressed beyond
Bouresches; and on th