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A GEOLOGICAL WALK AROUND INDEPENDENCE SQUARE PORT OF SPAIN, TRINIDAD
Dr. Rollin Bertrand
(Trinidad Cement Ltd.)

Independence Square in downtown Port of Spain is the heart of the city and is the site of many historic and prestigious buildings. These buildings are of interest to an earth scientist since many are clad with well polished exotic rock types from all comers of the world. Most of the buildings are clad with imported stone, but there are a few examples of local stonework that will serve as good comparisons. While the use of local stone for cladding and as inputs in the local terrazzo industry flourished in the building boom of the late 70s, it is an industry that could be developed to provide attractive alternatives to imported cladding.
With the present trends in the economy we may not see the importation of Italian marble and European granites in the near future. While this may be the kind of breathing space that the local stone industry needs, it will mean the end of the introduction of exotic rock types which are useful aids to the teaching of the earth sciences in local educational institutions.
This guide is meant as a start to the study of the type and origin of the imported rocks that clad buildings in Trinidad and Tobago. There are still many unanswered questions about the cladding stone on the buildings of Independence Square as not much information was kept either by the architects or the owners. In spite of this, however, we decided to run the trip as it may stimulate interest and some of the mysteries may be solved by people who read the guide or come along on

The walk will start outside the newest, most prestigious and most controversial building the Eric Williams Financial Complex. It will proceed along Independence Square south to the Roman Catholic Cathedral and then continue along the north part of the square out to Wrightson Road to end at Holiday Inn (see Figure 4).

STOP 1 - The Eric Williams Financial Complex. This building was officially opened on March 29th, 1986; later than scheduled and with sensational cost over-runs. Its twin towers dominate the skyline of the city and it should be of interest to any earth scientist who understands the position of Trinidad with respect to the Caribbean Plate boundary and all the attendant implications with regard to earthquakes. I was very fortunate to be able to speak to the site structural engineer who gave a broad overview of the earth-quake resistant design of the building.
Port of Spain is built on an alluvial plain flanked on all sides by low grade metamorphic hills (mainly phyllites). The Laventille limestone is the only real exception to this. Historical documents have shown that much of lower Edward Street is land fill, certainly not the type of soil on which one would want to put such a tall building in a seismically active area. The area was cored and a stiff layer found at about 25', but due to the presence of unconsolidated material below it they eventually decided to bed the piles in a deeper layer approximately 80' from surface.
1900 piles were driven to an average depth of 80' with 560 below each tower. Three full-scale tests were carried out on selected piles which were tested to failure and some of the piles under the tower were tested up to their working load. The average thickness of the basement under each tower is 25'. The pile cap under each tower is a cellular raft' which is a combination of 9' x 6' beams and an 18" slab. All columns on the towers are tied to this as water storage for the building is also located in the basement for additional dead weight. The cross braces and the core walls in each of the towers were designed to resist earthquake forces with the former taking 15% of the forces and the latter taking 80-85%. Additionally, great care was taken in the detailing of the reinforcement.
Like most modern buildings, the Financial Complex does not possess ornate or extravagant exterior cladding.
The concrete walls are 'brush-hammer' finished. Of interest to the geologist is the floor both inside and outside of the building. The monotony of the concrete walkways have been broken by an English slate from the Lake District called Burlington Slate. This is an Ordovician slate forming part of the Skiddaw Slate Group. Fossil graptolites (eg. Didymograptus sp.) have been reported from this slate, thus confirming its age.

STOP 2 - The Gordon Grant Building.
This building was officially opened on 27th May 1959. Mence and More were the Chartered Architects while Arthur Brothers were the builders. Both the exterior and interior of the building are generously clad by Italian marble. The walls at street level exhibit an even-grained black marble with golden streaks of some iron rich impurity. White Italian marble was also used on the exterior of the building. The marble was supplied by the firm of Thomas Peake located at 76 Henry Street. Unfortunately all of the records concerning the supply of this marble have been lost.

STOP 3 - The George F. Huggins
Building was completed around 1952. All records and plans for the building were lost in a fire. Some of the more senior employees remember that Watkins and Partners were the architects and the Contractors were Ash and Watson. The external walls of the building at pavement level are clad with 'black granite'. These 'granites' are popular as facing stone but their geology is somewhat obscure. They have been described as profoundly altered granites in which the original white minerals have become peppered with dark inclusions of ferromagnesian minerals and iron ores which render them dense and black. Such altered rocks are typically found in the ancient Precambrian shelf areas of the world -Africa, India, or the Baltic region of northern Europe. In hand specimen the altered feldspar laths are clearly visible but the dark inclusions mask the less distinctive minerals.

STOP 4 - The Republic Bank Building is somewhat of a mystery as the building has been added to and renovated since the Bank acquired the property in 1896. Some major renovations which probably resulted in the structure that we see today were completed in 1962. The walls near the pavement are once again covered with what appears to be 'black granite'.

STOP 5 - The Royal Bank building was officially opened in 1987 and exhibits a beautiful facade of West African black granite supplied by Caribbean Marble of Barbados. The architects for the projects were Gillespie and Steele, and Keir Trinidad Ltd were the Contractors. The laths of feldspar are visible on close examination of the wall, but it is difficult to identify any other minerals.

STOP 6 - The William H. Scott Building (according to its owners) is not yet completed. It is however the first display of the use of local stone on a prestigious building in downtown Port-of-Spain. The material was obtained from Scott's Quarry, now owned by National Quarries, and is commonly used in Trinidad and Tobago as a facing stone. Its distinctive 'blue' colour clearly identifies it as one of the blue limestones of the Northern Range (Jurassic).

STOP 7 - The Roman Catholic Cathedral was completed in 1832 and its history has been briefly compiled in a document entitled an "Historical Sketch of the Roman Catholic Cathedral of the Immaculate Conception" by Sr. Marie Therese Retout, OP. The present building replaced the old wooden structure built in Tamarind Square in 1781. The new church was constructed from 1816 - 1832 and was built of the 'blue metal' from the Laventille quarries. The consecration of the cathedral took place on February 23, 185 1 by the first Archbishop of Port-of-Spain, the Most Reverend Richard Patrick Smith. The structure was damaged by two earthquakes; one in 1863 which resulted in a new roof being built, and another in 1968. The Cretaceous Laventille limestone is not the only geologically interesting stone in the building as the altar is made of Florentine marble. The 14 Stations of the Cross were carved out of Italian Travertine by William Earley.
STOP 8 Salvatori Building is a somewhat featureless modern building but is trimmed with 'blue pearl granite' or Larvikite. This is a widely known and admired ornamental stone on account of its schillerized phenocrysts of feldspar. These phenocrysts consist of two feldspars intimately intergrown namely oligoclase, largely antiperthetic, and alkali feldspar usually soda orthoclase or soda microcline. Together these make up 80 - 90% of the rock. The mafic minerals tend to be grouped in clusters. Chief among them are diopsidic augite and titaniferous augite, often with reaction rims of barkevikite. In some specimens lepidomelane is present; in others, particularly in the basic varieties, bronzite and iron-rich olivine are not uncommon. Apatite is generally abundant, and the typical iron ores are ilmenite and titaniferous magnetite. Some larvikites may carry a little sodalite, cancrinite or nepheline.

STOP 9 - The Bank of Nova Scotia is clad with contrasting Italian marble in black and white with a grey variety and some travertine. Watkins and Partners were the architects but they have not been able to trace the source of the stone.

STOP 10 - The National Commercial Bank is divided into two buildings, an older and a newer structure. Like the Bank of Nova Scotia no one that I have talked to knows anything about the cladding on the building, which is probably marble.

STOP 11 - Nicholas Court is also clad with Larvikite.

STOP 12 - The Bank of Commerce is a striking building clad with pink granite exhibiting very large pink feldspar crystals. Black slate was used on the steps and travertine was used extensively in the bank on counters and as panels on walls. The building was completed in 1971 with Prior, Laurenco and Nothnagel as the architects and Horsfield and Lloyd Ltd in association with Mitchell Construction Caribbean Ltd as the Contractors.

STOP 13 - Trinidad House was completed in 1936 and is clad with striking panels of blue pearl granite or larvikite. Ash and Watson were the architects but I have not been able to find out anything about the source of the stone.

STOP 14 - Furness Withey & Co. Ltd was completed in 1962 with Mence and More as the builders and Ash and Watson as the architects. The group of companies is presently assembling a collection of historic documents about the building. The source of the marble on the walls facing Wrightson Road was not found.

STOP 15 - Holiday Inn was completed in 1973 by the Commonwealth Holiday Inns of Canada. The floor in the main lobby is of particular interest to local geologists as it is a good example of the texture of some of the blue limestone that is available in Trinidad. The stone came from Coosals Quarry in the St. Joseph/Maracas valley where it is called local marble. Although attempts were made to slab the marble for the floor to get marble tiles, the highly joined nature of the rock made this impossible. It is set in terrazzo cement and presents quite a striking finish.

Although there are many interesting rock types on display in Independence Square, Port of Spain, the main problem with a survey of this nature is that many of the Companies that designed or constructed the buildings are no longer in existence. It would have been much more interesting if I could have found out the ages and geological setting of these rock types to give more depth to the field excursion.

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