God

 <h1> G</h1>od

HISTORY OF GIS

History of GIS

GIS has evolved out of a long tradition of map making. In many respects, modern GIS dramatically increases the amount of information that can be contained and manipulated in a map. On the other hand, many of the same cartographic conventions and limitations apply to digital maps. Like all models, maps are, by necessity, simplified representations of reality. Partly, this is for convenience; it becomes very difficult to draw and interpret multiple information themes on one map covering more than a very small area. (1) Before computers became widely available, thematic maps on plastic Mylar sheets could be laid on top of each other, revealing more information about an area than was possible with any single paper map. Ian McHarg’s classic landscape architecture text, Design with Nature, advocated a rational approach to site planning (which he termed physiographic determinism) by creating Mylar overlays depicting landforms, soil types, vegetation patterns, and geomorphic features. (2) Although the process was cumbersome and the amount of data limited, McHarg’s method looks remarkably like the output of contemporary GIS; colored thematic maps were generated that aided in planning. However, as Burrough and McDonnell note with all of these early systems, “The paper map and its accompanying memoir was the database.” (3) There could be no database of information directly linked to the map and no automation of spatial querying. A detailed history of GIS is not well understood because GIS technology evolved through multiple parallel but separate applications across numerous disciplines. (4) The development of the GBF-DIME files by the U.S. Census Bureau in the 1960s marked the large-scale adoption of digital mapping by the government. This system led to the production of the Census TIGER files, one of the most important socioeconomic spatial data sets in use today. Important geographic work was also being done at universities throughout the 1950s and 1960s. A grid-based mapping program called SYMAP, developed at the Laboratory for Computer Graphics and Spatial Analysis at the Harvard Graduate School of Design in 1966, was widely distributed and served as a model for later systems. (5) These early GIS packages were often written for specific applications and required the mainframe computing systems found usually in government or university settings. In the 1970s, private vendors began offering off-the-shelf GIS packages. M&S Computing (later Intergraph) and Environmental Systems Research Institute (ESRI) emerged as the leading vendors of GIS software. (6) In 1981, ESRI released Arc/Info, a standard package which ran on mainframe computers. (7) As computing power increased and hardware prices plummeted in the 1980s, GIS became a viable technology for state and municipal planning. (8) In 1992, ESRI released ArcView, a desktop mapping system with a graphical user interface that marked a major improvement in usability over Arc/Info’s command-line interface. (9) By the early 1990s, GIS initiatives existed in all fifty states. (10) In the late 1990s, GIS was being adopted slowly on the sub-municipal level by neighborhood organizations and community-based agencies. The development of ArcView for Microsoft Windows and ArcIMS, which enables distributed mapping and spatial analysis over the Internet and eliminates many of the hardware and licensing expenses of a full software package, has increased the availability of spatial data to marginalized and underfunded groups. Although access to both GIS software and spatial data sets has improved, the adoption of GIS as a planning or research tool still represents a significant commitment by community organization. (11) Next section: GIS in Rhode Island

1. Monmonier, M. (1996). How to Lie with Maps. Chicago: University of Chicago Press. 2. McHarg, I. (1992). Design With Nature (2nd ed.). New York: John Wiley and Sons. 3. Burrough, P. A., McDonnell, R. A. (1998). Principles of Geographical Information Systems (2nd ed.). New York: Oxford University Press. 4. Pickles, J. (1999). Arguments, Debates, and Dialogues: the GIS-social Theory Debate and the Concern for Alternatives. In P. A. Longley, M. F. Goodchild, D. J. MacGuire, and D. W. Rhind (eds.). Geographical Information Systems: Principles, Techniques, Applications, and Management (2nd ed.). New York: John Wiley and Sons. Antenucci, J. C., Brown, K., Croswell, P. L. and Kevany, M. J. (1991). Geographic Information Systems: A Guide to the Technology. New York: Van Nostrand Reinhold. 5. Mark, D. M., Chrisman, N., Frank, A. U., McHaffie, P. H. and Pickles, J. (1997). The GIS History Project. Retrieved 15 January 2001 from the World Wide Web: http://www.geog.buffalo.edu/ncgia/gishist/bar_harbor.html Antenucci, J. C., Brown, K., Croswell, P. L. and Kevany, M. J. (1991). Geographic Information Systems: A Guide to the Technology. 6. Antenucci, J. C., Brown, K., Croswell, P. L. and Kevany, M. J. (1991). Geographic Information Systems: A Guide to the Technology. 7. History of ESRI. Accessed 26 April 2001: http://www.esri.com/company/about/history.html

A NEW OCEAN THAT WI LL DIVIDE THE CONTINENT OF AFRICA

The theory of the continental drift is still alife////
In 2005 a 60kilometre long crack was discovered along the Afah region of ethiopia, and it pushed apart by 8miters within 10days.
     This is mainly as aresult of molten magma from the eath crust and crustal instability.
if this phenomenon continues at the rate it seem now,
The somali plate will will drift off, the horn of africa will fall away and a new ocean emerges...
      Dont worry this will not happen anytime soon not in your life time we are speaking of 5-10 million years from now.

Continental Drift and Plate Tectonics

In 1912 Alfred Wegenerpublished a theory to explain why theEarth looked like a huge jigsaw. He believed the continents were once joined forming a supercontinent he called Pangaea. Over 180 million years ago this supercontinent began to "break up" due to continental drift.

During the 20th Century, scientists developed the theory of Plate Tectonics. The theory suggested that the crust of theEarth is split up into seven large plates (see map below) and a few smaller ones, all of which are able to slowly move around on theEarth's surface. They float on the semi-molten mantle rocks, and are moved around by convection currents within the very hot rocks.