The Beagle and the Rise of the Andes – Part II

Continuing with the previous post regarding the rising of the Andes Mountains and the comments of Darwin while on his voyage on the Beagle regarding this monumental event.

The Beagle's voyage and stops around the lower part of South America

 

On August 14, Darwin saw and collected many shells along the coast. After much surveying and collecting, Darwin found support for his idea that the western side of South America was slowly raising above sea level. The next day he returned to the valley of Quillota, crossed the ridge of Chilecauquen, then to Hacienda de San Isidoro at the foot of Bell Mountain, where he found more evidence for his theory.
    Around 11:30 on the morning of the 20^th a terrible earthquake hit the town of Valdivia. It lasted three minutes and the devastation was horrible - nearly every building in the area was destroyed. Darwin returned to the Beagle on the 22nd which sailed from the ruined town of Valdivia to the city of Concepcion, and as they sailed into the harbor, they saw, like at Valdivia, this town had also been devastated by the earthquake. On March 4^th, the Beagle entered the Harbor of Talcuhano near Concepcion. As at Valdivia, nearly every house around the harbor was destroyed. While the Beagle tried to make anchorage in Talcuhano Harbor, Darwin was dropped off at the island of Quiriquina. Here he explored around the coastline of the island and found several expanses of fresh marine rock that had risen a few feet above sea level due to the earthquake.

Fossilized coastal sea shells imbedded in rock on top of the Andes mountains proved to Darwin that even at this height, this area had once been under the ocean and had risen upward during the time of man

 

    Darwin also noticed raised shell beds on the cliffs above and became very excited about this find, as it was direct evidence that the Andes mountains, and indeed all of South America, may be very slowly raising above the ocean. These discoveries added much weight to Charles Lyell's theory that land masses rose up in tiny increments over extremely long periods of time. Given this fact, Darwin accepted the idea that the earth must be extremely old. The next day Darwin went by ship to Talcuhano Harbor where a tidal wave had destroyed nearly everything, and from the shore he rode by horse to the town of Concepcion to meet up with Capt. FitzRoy.

On his trip over the Andes, Darwin discovered Calceolarika uniflora, commonly known as “Darwin’s Slipper,” a unique plant high up in the Andes. He also discovered that the Andes were a young mountain range and had recently risen upward out of the ocean

    Later, on a trip over the Andes from Valpairaiso to Mendoza, Argentina, he found more sea shells, this time high in the mountains that he realized once at been upon the seashore. Numerous other discoveries in the Andes convinced him that at one time, the Andes were at sea level and the eastern shore of South America lapped the land upon which he walked, but was now several hundred miles to the east.
    In another area and along another line of thought, researchers from the Unversidade de Sao Paulo (USP), in studying the evolutionary process of diversification of a group of tube-dwelling anemones in the South Atlantic Ocean for four years, researchers obtained an unexpected result: the biological investigation ultimately contributed results that reinforced the geological theory that the Amazon basin was occupied by an inland sea that linked the Caribbean to Uruguay.

The initial objective of the study published in PLoS One was to use genetic and molecular analysis to identify the precise evolutionary moment of differentiation of the two tube-dwelling Atlantic Ocean species of Isarachnanthus anemones, a genus belonging to the taxonomic group Ceriantharia. 
    The results showed, however, that the most probable scenario for the diversification of the two species—and a third found in the Pacific Ocean—was consistent with the theory of the so-called “Middle Miocene Amazon Seaway.”
     According to this theory, an inland sea connected the Caribbean to the current region of the coast of Uruguay, cutting across the continent. In this period, most of the area of modern-day Brazil would have been an island separated from the rest of South America by an inland sea.
    The article was prepared by researchers of the departments of Zoology and Genetics and Evolutionary Biology at the USP’s Biosciences Institute (IB-USP), the Caribbean Research and Management of Biodiversity (CARMABI) in Curacao (Dutch Antilles) and the Institute for Biodiversity and Ecosystem Dynamics (IBED) at the University of Amsterdam.

FAPESP funded the study through the project “Sistematics, life cycle and reproductive patterns of jellyfishes,’” conducted under the auspices of BIOTA-FAPESP and coordinated by André Morandini (left), also a co-author of the article and professor at IB-USP.
    According to the first author of the article, Sérgio Stampar, who is pursuing post-doctoral studies at the Zoology Department at IB-USP under the supervision of Morandini, there have not been new studies on tube-dwelling Isarachnanthus anemones in Brazil for 50 years because of the difficulty of collecting specimens of this group, which is only found at night on marine substrates.
    “Our idea when we began this study was to resume studies on this forgotten group of cnidaria. We collected samples in several regions of the Atlantic Ocean and obtained large numbers of these organisms. In addition to routine morphological studies, we began to conduct unprecedented genetic analyses on these tube-dwelling anemones,” Stampar comments in an interview with Agência FAPESP.
    According to Stampar, the phylogenetic analyses indicated that only one type of tube-dwelling anemone occurred in the past. This organism, the ancestor of all Isarachnanthus included in the study, inhabited the North Atlantic Ocean, most likely near the latitude of the outlet to the Mediterranean Sea. It is probable that this species crossed the ocean and made its way to the Caribbean.
    “We discovered that from a genetic standpoint, the species in Brazil, Isarachnanthus nocturnus, was more closely related to the species found in the Pacific, Isarachnanthus bandanensis, than to that in the North Atlantic, Isarachnanthus maderensis. This finding surprised us because we thought the two species in the Atlantic would be closer,” said Stampar.
    In principle, the South Atlantic species, having changed more recently, could have reached more southerly regions along the coast of South America as a result of transport by ocean currents. However, this dispersal scenario is not possible because geological studies show that at that time, the currents flowed as they do today, from south to north. Therefore, the organisms would have had to travel by another route.
    ”It is virtually impossible for the South American tube-dwelling anemones to have come directly from the Atlantic. Nevertheless, the molecular and DNA analysis that we conducted allows us to estimate that these organisms reached the South Atlantic, which coincides with geological speculations on the existence of an inland sea that cut across South America. It is very probable that this was the route taken by anemones,” explains Stampar.

The seaway would have connected the region that is today the Caribbean, on the coast of Venezuela, to modern-day Uruguay, extending throughout the South American continent, covering the regions that are today Mato Grosso, Mato Grosso do Sul, Amazonas and Acre. When this inland sea closed, the anemones that had reached the South Atlantic would have been isolated, initiating the process of diversification into another species.
    “The geological process would explain the isolation of these anemones, which would allow for diversification of the nocturnus species when the inland sea closed and the population was segregated in the South Atlantic,” says Stampar.
    The point of all of this, no matter what subject, sea species, geological evidence, sea shells, plant life, etc., all indications as discovered by credited scientists in these fields, lead to the improbable, but obvious conclusion by them, that South America was once under water, that an inland sea through the present day continent once existed, creating an eastern sea about where the Andes is now located that ran eastward, in some cases clear to the present area of the east coast, that Panama was once disconnected above the surface to Colombia and the rest of South America, and that the Andes were along the coastal regions of a long, narrow island making up the western coastal region of South America.