158 Route 26. PETERSBERG.
The Stadhuis, or Hotel de Ville, with its clock-tower, situated
in the great market-place, contains several pictures of the Dutch
School and well-executed tapestry representing the history of the
Israelites in the wilderness. The town-library is also in this
building. Mastricht boasts of several very ancient churches. That
of Notre Dame, or the Lieve Vrouwenkerk, a late Romanesque
edifice of the 11th cent., has been disfigured by subsequent addi¬
tions, especially the unsuitable vaulting of the last century.
The Cathedral of St. Servaas belongs in its older parts to the
11th or 12th cent., but the interior was subsequently restored in
the Gothic style. One of the altar-pieces is a Descent from the
Cross by Van Dyck. The modern statue of Charlemagne by W.
Geefs was executed in 1845.
The principal attraction at Mastricht is the subterranean laby¬
rinth of sandstone quarries which honeycomb the *Petersberg in
every direction, having been worked for upwards of a thousand
years. A visit to them occupies ll/.2—2 hrs.; attendance of a guide
indispensable (see p. 157). They are usually entered near the house
of the burgomaster of the village of St. Peter, 3/4 M. to the S. of
Mastricht, whence visitors ascend gradually to the upper outlet,
near the suppressed Servite monastery of Slavanden (nowthe Casino,
the property of a club); but, if preferred, the excursion may be
made in the reverse direction.
The Petersberg range, extending from Mastricht to Liege, is
composed of a soft, yellowish, sandy aiul calcareous stone, or chalky
tufa, which has been deposited by the water of the ocean, and
contains numerous conchylia, fragments of coral, sharks' teeth,
fossil turtles, bones of a gigantic marine monster resembling a
crocodile , and other traces of its remote subaqueous origin. Many
of these interesting fossils are preserved in the collection at Liege
(p. 150), and others may be seen at the Athenaeum at Mastricht.
The so-called orgues geologiques, cylindrical openings of 1—7 ft.
in diameter, and generally vertical, perforating the formation to a vast
depth, and now filled with clay, sand, and rubble, are a singular
phenomenon which has not yet been satisfactorily explained. It is
conjectured that they were originally formed by submarine whirl¬
pools , the action of whicli is known to produce circular orifices in
rocks of much harder consistency, and that they were afterwards
enlarged by the percolation of water impregnated with carbonic acid.
The economical value of the stone consists in the facility with
which it is sawn into symmetrical blocks, and in its property of
hardening on exposure to the atmosphere. The galleries, which
vary from 20 to 50 ft. in height, are supported by pillars averaging
15 ft. in diameter, left for the purpose. The first excavations are
believed to have been made by Roman soldiers, and the same
systematic mode of working has been observed ever since that