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Coastal and Marine Geology Program > St. Petersburg Coastal and Marine Science Center > Coasts of Colombia

Coasts of Colombia

Coasts of Colombia
Pacific Coast:
Introduction
Serranía del Baudó (Baudó Range)
Cabo Corrientes-
Togoromá
San Juan River Delta
Málaga Bay - Buenaventura Bay
Buenaventura Bay - Guapi
Patía River Delta
Tumaco Bay
Mira River Delta
Gorgona Island
Malpelo Island
References
Caribbean Coast:
Introduction
Guajira Peninsula Coast
Sierra Nevada de Santa Marta Coast
Magdalena River delta and Santa Marta lagoon complex
Barranquilla - Cartagena coast
Southern Caribbean coast
Gulf of Urabá
References
Project Contact:
Robert Morton

Pacific Coast: Tumaco Bay

Tumaco Bay, located between the Patía and Mira deltas, is the largest embayment of the entire Pacific Coast of Colombia (Fig. 35). The bay is a shallow (30 m maximum depth), semi-protected area located on an active tectonic area with N 30º E structural trends.

Geomorphic classification of the Tumaco Bay and Mira River delta.
Figure 35. Geomorphic classification of the Tumaco Bay and Mira River delta. Modified from Correa (1996).

The Tumaco Bay northern and east coasts are dominated by intertidal flats and by 10 to 40-m-high, vertical to sub-vertical cliffs cut into horizontal to sub-horizontal mudstones (Fig. 36). Cliff retreat is slow in most sectors, but rockfalls and slumping are caused by seismic events and occasionally strong rain. Minor pocket beaches and wave-cut platforms can be found along the eastern cliffs of Tumaco Bay (Fig. 37). Tidally influenced estuaries with lobe-shaped bars and tidal flats backed by extensive mangrove swamps (Fig. 38) characterize the southeastern shores of Tumaco Bay.

Cliff shoreline of Tumaco Bay northern shores.
Figure 36. Cliff shoreline of Tumaco Bay northern shores. Recession of 20-m-high vertical cliffs cut into horizontal mudstones by rockfalls originated during the Tumaco earthquake of December 12, 1979. Photo by I. Correa.

Typical cliff morphology and pocket beaches of the eastern side of Tumaco Bay.
Figure 37. Typical cliff morphology and pocket beaches of the eastern side of Tumaco Bay. Photo by I. Correa.

Radar image showing the southwestern shores of Tumaco Bay and the northeastern area of the Mira River delta.
Figure 38. Radar image showing the southwestern shores of Tumaco Bay and the northeastern area of the Mira River delta. Dark rectangular areas are large excavations in the mangrove swamps for aquaculture facilities. Reproduced by permission of Instituto Geográfico Agustín Codazzi (IGAC) and INTERA Information Technologies (STAR-1 radar).

At its southwestern part, highly unstable sandy barrier and bar complexes migrating from the northwestern Mira delta front the internal shores of Tumaco Bay. Most of the city of Tumaco (Fig. 39) is located on the La Viciosa and El Morro islands, the two largest sandy barriers. Both barriers are subject to rapid cycles of accretion and erosion as intertidal bars are deposited and destroyed (Fig. 40). Offshore sandy intertidal flats (Figs. 41 and 42) have protected La Viciosa and El Morro from the direct impact of the 1902 and 1979 earthquake-generated tsunamis.

Tumaco city.
Figure 39. Tumaco city, mainly located on Tumaco Island (center) and El Morro Island (top), view to the north. Reproduced by permission of Observatorio Sismológico del Suroccidente Colombiano (OSSO) - Universidad del Valle.

El Morro hills, on the northern end of Isla El Morro.
Figure 40. El Morro hills, on the northern end of Isla El Morro. A tide gauge located on the ocean side of this outcrop shows a relative fall in sea level of about 4 cm for the last 50 years, indicating coastal emergence along an uplift crossing Tumaco Bay. Photo by I. Correa.

Digitated sandy-muddy intertidal bar along the El Morro Island frontal beaches.
Figure 41. Digitated sandy-muddy intertidal bar along the El Morro Island frontal beaches. Photo by A. Tovar.

The recently formed "El Guano" sandy bar system seaward of Tumaco and La Viciosa islands.
Figure 42. The recently formed "El Guano" sandy bar system seaward of Tumaco and La Viciosa islands is presently growing at the same place occupied by a similar system of offshore bars that was destroyed by the tsunami associated with the December 12, 1979 earthquake. Photo by A. Tovar.

Coastal and Marine Geology Program > St. Petersburg Coastal and Marine Science Center > Coasts of Colombia

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