Triangulation points at Rif St Marie

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Coral Estate 20150409 033 smallOn Thursday April 9, 2015 a small group of the archaeology sleuths consisting of Fred, Hetty, Carel and Eliane Haseth as his guest and I, went to the former plantation Rif St. Marie. We parked our cars with permission from the management on the parking lot of Coral Estate and went from there looking for two triangulation points in this area. According to the Kadaster map from 1993 the triangulation point with the number DP 9 is located to the Southeast of the entrance of Coral Estate and according to the Werbata map from 1909 the triangulation point WB32 is located to the North of the entrance. The first one is placed by Kadaster and the second one is placed by Werbata in the beginning of 1900 for the first topographical map of Curaçao.

Triangulation points are used to measure distances between points. First a baseline is established by positioning two points with a known distance on hill tops. A third point is positioned within sight distance of the two others and from each of the endpoints of the baseline the exact angle between the baseline and the line to the third point is measured. With this information, the exact length of the baseline and the exact angle from each of the endpoints to the third point, the distance from the endpoints to the third point can be calculated. In this way the exact length of the three sides of the first triangle are known. This process is then repeated to other points. A network of points with known distances between these points is so created as a first map of the area, in this case the island of Curaçao. The next step is to investigate in detail the area between these points at ground level to bring in the details of the area. This last step is nowadays done by aerial photography which is a far quicker method to cover large areas. The disadvantage is obviously that objects that are covered by vegetation are not detected with aerial photography. As a consequence the Werbata map has far more details than the later maps created by Kadaster.

In most cases Kadaster reused the former triangulation points positioned by Werbata by building a new triangulation point on top of the old one. And Kadaster added extra triangulation points. This approach means that most Werbata points have a Kadaster triangulation point on top. A Werbata triangulation point on its own is rather rare.
In this area Kadaster decided to use another part of the same hill, the Seru Kabritu, to position a Kadaster triangulation point leaving the old Werbata point intact.

First we went to the Kadaster point. That was reasonably easy because for a large part of the trip the vegetation was rather open. We just had to be careful not to touch one of the many Bringamosa plants in this area. On top of the hill it became more difficult because there were a lot of Wabis and Prickly pear cacti. And we had to walk close to the edge of the cliff while avoiding the plants.
After taking pictures and the exact location of this point we went back to the parking lot for the second part of our search, the Werbata triangulation point. Also here the hike started reasonably easy through an area with a lot of Brasia's, some of which were rather impressive. Higher on the hill also here the vegetation became denser. There we first found a dry-stone wall. After crossing that wall we reached the Werbata point. This is in remarkably good condition given the fact that it is more than 100 years old. Especially the clear imprint of the text Triang No 32 is nice.
Close to this point we found a lot of case bottles and also some bottoms of the 1 liter beer bottles produced by P & S Rendorp from Amsterdam. These date probably from the mid 1800's. It is unclear why there is such a large concentration of old bottles in this area.

After descending to the road Fred, Hetty and I decided to go to the strange layered rock to the left of the road to Coral Estate. This is obviously limestone but in this case with a layered structure. When we neared the rock some bees found us unwelcome guests and they started an attack. Luckily only I was stung and we could drive off the bees by spraying with Baygon, one of the necessary tools in our backpack.
So we decided to approach the rock from the other side where we had a good view of the layered structure. Unknown is what caused this layering.
Also on our way back we made a large detout to avoid the bees. Safely back at the parking lot we decided to end the hike for this day..