*7.3.3 Interpretation and sketch geological maps*

When samples are taken, their geochemical anomaly helps to find ore bodies. Stream sediments is an exploration tool, which plays a significant role in geochemical exploration by identifying possible sources of anomalous element concentration. Sampling is done on rock debris, soil or other materials which has undergone erosion and transportation within a catchment basin upstream of a sampling site. It is thus representative of the geochemistry of materials from the upstream drainage basin. The collection and analysis of these stream sediments (silt, sand, mud, clay) in a stream or riverbed, either dry or wet are common methods for exploration. Stream sediments are used for geochemical analysis for enhancement of geological understanding.

Rock types can be differentiated by geochemical signatures in stream sediment data. But rocks can also help to draw sketch of geological maps. Those geological maps are then compared to the existing ones in other to understand how wrong were the map or not. The **Figure 21A** and **B** below shows a sketch of geological map built from the granites sampled in the Meiganga region.

### **7.4 Disadvantages of using GIS**

Though GIS could benefit users from different disciplines it also has some disadvantages:


### **Figure 21.**

*(A, B) Sketch of geological map of the study area derived from sampled areas.*


*DOI: http://dx.doi.org/10.5772/intechopen.106632 GIS and Database Management for Mining Exploration*

#### **Figure 22.**

*Example of error. When zoomed, the point 1,015,308 which seems to be well placed on the stream, is shifted for more than 100 m.*


### **7.5 Improvements on GIS**

GIS of the future may be very well done if already the following aspects are understood and objectives outlined following, other aspect such as: Planning, system design, implementation, maintenance of the software should be observed.

#### *7.5.1 Planning*

*Your plan should answer the question: What information do I hope to gather?* In planning its major contribution is to give us with an organized set of data which can help professionals to manage complex scenarios relating to the selection of site, environment impact, study of ecosystem, managing risk regarding the use of natural resources, sustainability issues, managing traffic congestion, routing of roads and pipelines etc.

Precise and accurate data is the core driving factor of any successful project. GIS is equipped with almost all those tools and functions that enables user to have access to the required data within a reasonable time.

Analysis is one of the major and most influential phases. Analysis guides us about the validity or correctness of design or we can say that analysis is a method which supports our design. Some of the analyses that can be performed by GIS are: water distribution analysis, traffic management analysis, soil analysis, site feasibility analysis, environment impact analysis, volume or area analysis of catchment, river or canals pattern analysis, temperature and humidity analysis, elevation etc. The construction phase involves the assemblage and putting into place the various tools to attain the objectives already established.

Lastly the operations phase, is the execution of a set of activities using all tools to acquire the necessary data. This last phase may, if not always necessitate a deployment of a qualified person to the field to obtain useful information.
