The Earliest Inhabitants: The Dynamics of the Jamaican Taino
by Lesley-Gail Atkinson
by Lesley-Gail Atkinson
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
YOUNGER<br />
GROUP<br />
OLDER<br />
GROUP<br />
Limestone<br />
Sediments o<strong>the</strong>r than limestone and<br />
some volcanic lavas<br />
Sediments<br />
Lavas, sediments and igneous<br />
intrusions<br />
Metamorphic rocks<br />
1. St James<br />
2. Trelawny<br />
3. St Ann<br />
4. St Mary<br />
5. Portland<br />
6. Hanover<br />
7. Westmoreland<br />
8. St Elizabeth<br />
9. Manchester<br />
10. Clarendon<br />
11. St Ca<strong>the</strong>rine<br />
12. St Andrew<br />
Figure 9.1 Simplified geological map <strong>of</strong> Jamaica showing parishes<br />
in hand specimens. It is <strong>the</strong>refore not usually possible to say whe<strong>the</strong>r <strong>the</strong> original<br />
rock was, for instance, lava, a conglomerate or a sandstone before it was<br />
metamorphosed. Sometimes on a sawed section or under <strong>the</strong> microscope it<br />
may be possible to see a few relict structures or textures indicative <strong>of</strong> its origin.<br />
Most <strong>of</strong> <strong>the</strong> metamorphic rocks <strong>of</strong> Jamaica have not undergone a major<br />
alteration and can be considered to be only lightly metamorphosed. <strong>The</strong>y<br />
appear as extremely fine-grained massive rocks lacking structure. Indeed, <strong>the</strong><br />
crystals are so small that very <strong>of</strong>ten it is difficult to identify <strong>the</strong>m under <strong>the</strong><br />
microscope.<br />
<strong>The</strong> most common <strong>of</strong> <strong>the</strong>se rocks are coloured green, and <strong>the</strong> term “greenstone”<br />
seems as good as any. Less common is a black-coloured variety (“blackstone”),<br />
which occurs interlayered with <strong>the</strong> greenstone; where <strong>the</strong> two occur<br />
in cliff faces, <strong>the</strong>y are usually strongly folded. Marble (metamorphosed limestone)<br />
also occurs interlayered with <strong>the</strong> greenstone – for example, at <strong>the</strong><br />
quarry at Serge Island Estate in <strong>the</strong> east arm <strong>of</strong> <strong>the</strong> Morant River, sou<strong>the</strong>rn<br />
Blue Mountains. A higher degree <strong>of</strong> metamorphism results in a coarsergrained<br />
rock which shows a foliation <strong>of</strong> crystals. Such a rock is called a schist<br />
and tends to split easily.<br />
134 T HE E ARLIEST I NHABITANTS