Geology Reference
In-Depth Information
Table 1. Values of water and air temperature, rainfall and water discharge. Water temperature is the mean of
5 sampling sites at the end of December and June. Air temperature, rainfall and water discharge are expressed
as the mean of the values corresponding to the same months that define the cool and warm periods of the
sedimentation rate measurements. Data provided by the Agencia Estatal de Meteorolog
´
a and Confederaci
´
n
Hidrogr
´
fica del Ebro (gauging point of Nu
´
valos)
Periods
Air T
(8C)
Water T
(8C)
Precipitation
(mm)
Water discharge
(m
3
/s)
Oct. 02 - Mar. 03
8.70
6.9
326.5
1.14
Apr. 02 - Sept. 02
18.63
18.9
442.3
0.62
Oct. 01 - Mar. 02
6.72
10.1
119.0
0.69
Apr. 01 - Sept. 01
18.99
16.5
189.0
0.75
Nov. 00 - Mar. 01
8.54
10.1
249.8
1.03
Apr. 00 - Oct. 00
18.37
14.5
416.4
0.71
Nov. 99 - Mar. 00
6.70
11.1
178.6
1.12
centre and occupies an area of around 2500 m
2
.
The lake empties into the River Piedra via an artifi-
cial channel downstream of the Park (Fig. 1c).
The climate of the area is of the continental
Mediterranean type with strong seasonal contrasts.
For the studied period, the mean annual air tempera-
ture was around 12 8C, with mean montly values of
5 8C in January and 23 8C in July - August. Water
temperature ranged from 6.9 - 11.1 8C in autumn/
winter and from 14.5 - 18.9 8C in spring/summer.
The mean annual rainfall was around 400 mm, irre-
gularly distributed, with maxima in spring and
autumn (Table 1).
The drainage area of the River Piedra is about
1545 km
2
. From 1999 - 2003 the mean water dis-
charge ranged between 0.62 - 1.14, with a mean of
0.87 m
3
/s (Table 1). The river receives important
water inputs from a Mesozoic carbonate aquifer
(Lower Jurassic and Upper Cretaceous limestones
and dolostones around 500 m thick). The strong
influence of underground water makes water dis-
charge show only slight monthly variations. These
small monthly variations have a cyclical pattern
with maximum values in winter and minimum
values in summer. Some exceptional floods caused
by heavy rain in spring and summer had a strong
influence on the tufa sedimentary system by trigger-
ing
help
understand
the
sedimentary
processes
that
govern
present
and
ancient
tufa
formation
in
Mediterranean regions.
Geological context, climate and hydrology
The Monasterio de Piedra Natural Park is an excep-
tional place near the town of Calatayud, between
Madrid and Zaragoza (NE Spain) (Fig. 1a). The
Cistercian monastery (built in 1195AD) is at an alti-
tude of 786 m, although the surrounding uplands
range between 850 and 1000 m. From a geological
point of view the study area is within the Iberian
Range (Fig. 1a), a NW - SE trending alpine intra-
plate fold belt. Near the Park, the following
sequence is found (Fig. 1b): Palaeozoic shales and
quartzites, Triassic sandstones, dolostones and
gypsum-rich marls, Lower Jurassic dolostones,
Lower Cretaceous sands and a thick Upper Cretac-
eous succession of limestones and dolostones.
Miocene conglomerates, sandstones and mudstones
overlay this sequence. All these units are slightly
deformed by NW - SE trending folds and faults.
During the Quaternary the River Piedra formed a
number of gorges and small canyons in which
thick Upper Pleistocene and Holocene tufa outcrops
are common (Arenas et al. 2004).
The River Piedra flows from south to north
through the Iberian Range (Fig. 1b). Its longitudinal
profile shows several important knickpoints with
large waterfalls, two of which (c. 15 and 35 m
high) lie within the Park (Fig. 1c). At the lower
part of the Park there is a shallow lake - Lake
Espejo - that reaches a depth of some 2 m at its
strong
erosion
processes
that
affected
the
sedimentary record.
At present the river presents highly active tufa
formation, particularly near the Monasterio de
Piedra Natural Park, as shown by present-day moni-
toring (Arenas et al. 2004; V´zquez-Urbez et al.
2005, V´zquez-Urbez et al. in press).
Fig. 1. (Continued)(c) Course of the River Piedra, with location of the vertical waterfalls and Lake Espejo within
the Park and location of tablets. Tablets 1 to 6 were set on the river bed, tablets 10 and 11 in stepped waterfalls on the
river banks, tablets 7, 8, 9, 12 and 13 in stepped waterfalls outside the main stream area, and tablet 14 in the Iris
Cave behind the Cola de Caballo waterfall.
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