101
Abstract The Iguazu Falls are one of the most beautiful
in the world because of the combination of a high and
wide structural step across a fluvial system with large
water discharge and the tropical environmental loca-
tion that sustains an exuberant forest and high biodi-
versity. The geology of the area consists of three layers
of basalts that give a staircase-type shape to the falls.
The Iguazu River is about 1,500 m wide above the
falls and forms many rapids between rock outcrops and
small islands. The falls have a sinuous arch-like head
2.7 km long, and part of water volume enters a canyon
80–90 m wide and 70–80 m deep, forming the spectac-
ular “Garganta do Diabo” (Devil’s Gorge). Part of river
water enters the canyon by its left side and generates a
front with 160–200 individual falls that form a unique
wall of water during floods. Although no absolute ages
exist on the evolution of the fluvial system, it has been
suggested that the falls have been continuously
wandering upstream to its present position by progres-
sive headwater erosion at a rate of 1.4–2.1 cm/year in
the last 1.5–2.0 million years. The falls are recognized
as UNESCO World Heritage property and regarded as
a Geomorphological Site by the Brazilian Commission
of Geologic and Paleobiological Sites – SIGEP.
Keywords Iguazu falls • basalts • Paraná basin
• World Heritage • Geomorphological Site
11.1 Introduction
Waterfalls are impressive geomorphological features
with strong scenic value. Considering that South
America is drained by huge and complex drainage sys-
tems, especially in tropical areas, and that the largest
South American rivers contribute to 28% of the total
fresh water to the oceans, waterfalls and long series of
rapids are common features in South American land-
scapes. The continent hosts the highest fall on Earth,
Angel Falls in the Gran Sabana of Venezuela, and the
mightiest one – according to many – the Iguazu Falls
(Fig. 11.1). The name Iguazu comes from the Tupi-
Guarani native language and means Great ( guassu)
Water ( y).
Without any doubt, the world famous Iguazu Falls
are the most spectacular waterfall of South America
and one of the most beautiful worldwide due to a com-
bination of remarkable factors: the existence of a high
and wide structural step across a fluvial system with
large water discharge and the tropical environmental
location that sustains an exuberant forest and high
biodiversity.
The falls developed across the Iguazu River and are
located at the border of Argentina and Brazil (Figs. 11.2,
11.3). The area is covered by tropical forest and the
mean annual rainfall is 1,712 mm. The relief oscillates
between 100 and 300 m a.s.l. The falls are part of the
Bi-National Park of Iguazu (Argentina and Brazil).
The Argentinean park was created in 1934 and the
Brazilian park in 1939 and both spread on near 2,500
km
2
. The Argentinean area was recognized as UNESCO
World Heritage in 1984 and 2 years later, in 1986, the
site was extended to include the Brazilian side as well.
Iguazu Falls are regarded as a Geomorphological Site
by the Brazilian Commission of Geologic and
Paleobiological Sites – SIGEP (Salamuni et al. 2002).
With an annual mean of 1.5 million visitors, the falls
are among the main tourist spots for both countries.
The Iguazu River rises near the Atlantic Ocean in
the Serra do Mar range (c 900 m a.s.l.) and drains a
basin of 78,800 km
2
. It runs for 1,300 km (1,205 km in
Brazilian territory and 105 km along the Argentinean–
Brazilian border) and joins the Paraná River as its left
Chapter 11
Iguazu Falls: A History of Differential Fluvial Incision
José C. Stevaux and Edgardo M. Latrubesse
P. Migon ´ (ed.), Geomorphological Landscapes of the World,
DOI 10.1007/978-90-481-3055-9_11, © Springer Science+Business Media B.V. 2010