An exciting discovery – Sea Shells Far From Shore
By Richard Charan
By Editor, South Bureau
How else could the mind explain, he would say later, all these crystals and sea shells emerging from the ground? And at a place so far from the coast – eight miles at least – past hills and valleys and homes and highways?
A great hiding place, Bob Ramoutar first thought, when his giant excavator unearthed the shells while digging into a hillside in early September.
His discovery while clearing land for a housing development off rural La Cuesa Road, Freeport, has piqued the interest of researchers at the University of the West Indies. A suggestion that the find could have been a shell midden left behind by Trinidad’s early people (similar middens have been found in other parts of Trinidad) was dispelled by Dr Basil Reid, senior lecturer in Archaeology at the Department of History, University of the West Indies, when the massive scale of the find began to emerge.
Shells by the millions, no billions, some resembling what you might see washed up on a tropical beach, others the size of an adult’s hand, none having any business so far from the sea, the layman would think. And mixed up in it all, quartz (rock crystals).
This, Dr Reid said, might be something of interest to his colleague, Dr Brent Wilson, senior lecturer in Paleontology and Sedimentology, Petroleum Geosciences Programme, at UWI’s Department of Chemical Engineering.
Wilson has examined images of the shells found at the site – there are at least five distinct types, and made observations. The discovery, Dr Wilson said, would be sure to excite the Geological Society of Trinidad and Tobago, of which he is an executive committee member.
This is what Dr Wilson reported.
“I concur with Dr. Reid that this is most likely not a man-made shell midden: from the photographs showing the site, the number of shells is small compared to what one would expect in a midden. Also, they appear to be widespread. Instead, this appears to be a community of shells enclosed within a muddy deposit, and probably has a geological rather than an anthropogenic (man-made) origin.
The shells themselves are thick and heavy, one being an oyster. Many show a heavy ornament of ribs. Such molluscs typically live in shallow water, where the thick shells protect the creatures from damage during heavy seas. The ribs also confer strength and stability to the shells, a bit like steel added to the framework of a building (when the contractors remember put it in, that is!)
I would hesitate to give an age for these shells, other than to say that they do not look old in a geological sense (i.e., we may be talking thousands rather than millions of years). I shall assume that this is so. Sea level has not been constant throughout geological time, but has gone up and down as ice caps at the poles have alternatively melted and grown. At times when the ice caps are particularly small, sea levels will be high, the melt water being released into the oceans. Perhaps, then, the shells mark a time when sea level worldwide was higher than it is at present.
There is an alternative explanation: Trinidad is in an area where two of the world’s few crustal, tectonic plates meet. Southern Trinidad lies on the South American plate, while northern Trinidad lies on the Caribbean plate. (There’s a thing few realise: drive from Port of Spain to San Fernando and you go from the Caribbean to South America, the actual point of passing from one to the other not being far north of the Forres Park Flyover.)
Plate boundaries are characterised by tectonic activity — a fancy term for earthquakes. These occur as the plates rub together, producing uplift such as had formed the Northern and Central Ranges. The earthquakes can be very powerful and destructive to lives and property. (It was earlier this year suggested that Trinidad has enough stress stored within the Central Range to produce a magnitude 7 earthquake. Unfortunately, we cannot say when it will take place.)
Perhaps, then, the shells mark a period of one or more major earthquakes, when a section of the seafloor was uplifted, bringing the shells with it.
It might be suggested that the shells were transported inland during a tsunami associated with an earthquake. However, this is highly unlikely. Tsunamis (and storm surges associated with hurricanes) are not capable of transporting such large shells far. Instead, the material they would wash inland is fine sand and microscopic shells just a few millimetres across”.
Bob Ramoutar intends preserving the site to allow researchers time to conduct a study.