Julie Zydek, Hydrogeologist
Geology of Cuba
By Julie Zydek
From March 18 to March 23, 2018, I visited Western Cuba with the Southeastern Geological Society (SEGS) to study outcrops and the geomorphology of the western part of the island. The geology of the Cuban archipelago is very complex as it has a history of volcanism, tectonic action, sea level transgressions and regressions, metamorphism, and sedimentary deposition. We were hosted by Cuban geologist Manuel Iturralde Vinent, the unsung hero of Cuban geology. He plays a fundamental role in preserving the integrity of the outcrops for future field trips, research, publishing, public outreach on geology, health, safety, and the Museo Nacional de Historia Natural in Old Havana. We were also hosted by a local travel guide named Osmin and tour bus driver, Jose Louis. During the first four days, we visited many outcrops in and between Viñales, Varadero, and Havana to observe the mountainous, coastal, and karstic terrains. The last two days were spent exploring Old Havana.
Viñales
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On the first day in Viñales, we received a presentation from Manuel about the geology and karst overview at the visitor center of Viñales Natural Park. Here there are many tower karst formations (Fm) and we witnessed the geomorphology of the Viñales valley and surroundings. We also visited the KT boundary and Paleogene foredeep deposit near Moncada. An email we received before the trip stated that Che Guevara staged hardware, munitions, and troops in anticipation of a U.S. invasion in the early 60s here.
On the second day, we visited the Jurassic-Cretaceous continental margin sections of Pangea to the Proto-Caribbean and Cuevo del Indio. The formations observed were the Middle Jurassic sandstone and shales (San Cayetano Fm), the organic-rich shales and limestones of the Jagua Fm, and the Kimmeridgian carbonate platform (both Jurassic in age) and Jurassic-Cretaceous boundary sections.
Fossil concretion near Viñales ©2018 Julie Zydek
KT Boundary
The KT boundary near Moncada demarcates an erosional contact between the Late Cretaceous age Moncada Formation and the overlying Manacas Formation. The Moncada Formation is composed of shocked quartz, vesicular impact melt fragments, and altered grains of possible impact glass. This Formation also contains cross-laminated ripple marks that occur in many horizons which indicate north to south trending paleocurrent directions with reversals. Additionally, variable grain size within the horizons is indicative of tsunami wave action.
Viñales KT Boundary ©2018 Julie Zydek
Viñales Stonehenge
The “Viñales Stonehenge” (so named by Manuel himself) in the Dos Hermanos valley are formed by vertically flowing water after rain events. This causes the limestone to be dissolved with pinnacle and other karren-like geomorphological features.
Viñales Stonehenge ©2018 Julie Zydek
San Cayetano Formation
Another featured observed in Viñales are the folds of the Early to Late Jurassic aged San Cayetano Formation that outcrop on La Palma Road. These inverted folds of sandstones and shales are the oldest known deposits of the Guaniguanico mountains. The deposition of this Formation occurred simultaneously with the break up of Pangea in the Mesoamerican area. The portion of this Formation observed on La Palma Road is made up of well-bedded, reddish to yellowish, fine to medium grained sandstones and shales. Muscovite and zircon are observed in the sandstones, and the Paleoproterozoic zircons are thought to have originated from western and northern parts of South America. The overlying Late Jurassic Jagua Formation contain fossiliferous concretions. Fossils recovered from this Formation include: dinosaur, fish, plesiosaur, pliosaur, metriorhynchus crocodile, pterosaur, and ammonites.
San Cayetano Formation observed in/near Viñales ©2018 Julie Zydek
Cuevo del Indio
Cuevo del Indio is a vadose zone cave, formed by the Cuyaguateje river (which flows inside the cave) cutting into the limestone hills (mogotes). It is home to many galleries that can be accessed by foot and by boat. The scallops seen on the walls were formed by currents.
Cueva del Indio room ©2018 Julie Zydek
Cueva del Indio scalloped wall ©2018 Julie Zydek
Varadero
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We left Viñales on the third day to head to Varadero, a popular tourist spot on a peninsula east of Viñales, for two days. Here we visited the KT boundary and the quaternary marine and coastal deposits, as well as allochthonous serpentinite ophiolites, Cretaceous arc rocks, and rocks from the Paleocene in the Havana-Matanzas area. We went snorkeling along a shallow reef at Playa Coral and inside Cueva de Saturno. The coral reef is currently recovering from sands which were imported to transform a rocky shore into a beach. However, wave action is removing the sands from the beach and the corals are recovering. We also visited Cueva Ambrosio, a protected cave that contains aboriginal drawings.
Cueva Ambrosio, Cuba ©2018 Julie Zydek
Cueva Ambrosio pictograph, Cuba ©2018 Julie Zydek
Serpentinite ophiolites (observed en route from Varadero to La Habana) ©2018 Julie Zydek
Bacunayagua Bridge
The Bacunayagua Bridge is one of the highest in Cuba and overlooks outcrops of Miocene age marls of the Cojimar Formation and limestones of the Guines Formation. To the south, the Yumuri valley cuts across Cretaceous volcanic sediments and mafic to ultramafic, late Cretaceous to Miocene age sediments.
Yumuri Valley, Cuba ©2018 Julie Zydek
Bacunayagua Bridge, Cuba ©2018 Julie Zydek
Terraces at Dupont and Hicacos
The shoreline in and around Varadero is dominated by rocky beach shores and unconsolidated dune deposits. Four marine terraces are identified, with the first identifiable terrace being from the Late Pleistocene age Jaimanitas Formation. The second identifiable terrace is several tens of meters away from the shoreline, in the Vedado Formation, which outcrops near the Hotel Nacional de Cuba in Havana. Terraces west of the Peninsula de Hicacos contain Sante Fe Formation cross laminated dunes made up of eolian calcarenites that reach heights of five to eight meters. In this area, as well as Dupont, tidal notches are apparent as erosional features of the terraces.
Hicacos and Dupont beach terraces ©2018 Julie Zydek
Havana
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We spent the last two days in Havana where we visited the Museo Nacional de Historia Natural in Old Havana and were given a guided walking tour by our local tour guide, Osmin, of the city. We visited the Hotel Ambos Mundos and the house Ernest Hemingway had once lived in at Finca Vigia. The hotel we stayed at was the Hotel Nacional de Cuba, which housed many celebrities and mobsters during Cuba’s heyday.
Julie is also an avid rower – check out this video she took of a sculler near Matanzas:
I received this interesting write-up from a hydrogeologist where I work named Julie Zydek, and I just had to share this with everyone! She went to Cuba on a field trip and summarized what she learned with lots of photos. Thank you, Julie!
Sandie