The overlapped area is detected by the camera from two different views in two different photos. The overlap between adjoining photos in a sequence along the line is about 55-60 %. Photographic surveys follow specified flight routes and take the photographs at regular spacing along the path. The information can be gathered more efficiently and safely than a ground traverse, although there is no substitute for direct observations. Color contrasts in exposed bedrock due to changes in rock type, or lithology, and can be traced on the photograph, to map out the contact. When the work was performed properly, there will be possible to know the structural features in a specific area, such as the direction and dip of the beds, fold direction, and fault plane dip. It is possible to get information on lithology, alteration and structures. Even, it is possible to get information on ground water movement, and this is influenced by fracture traces, karst features and aquifer recharge and discharge points such as springs. Photogeologic analysis provides data on local geology conditions which help to detect possible gold zones. Rock and soil color changes, or color anomalies, can be delineated and possibly investigated with ground traverses. In mineral exploration work, accurate topographic base maps are essential for recording geological observations. Most importantly, they are used to make accurate topographic base maps. Orthophotos are images which have the distortion rectified, and can be used directly for mapping purposes. There are many applications of photogeological methods in mineral exploration work as well as in the studies of environmental geology and geologic hazards. The map scale towards the center of the photo is different from the map scale toward the edges of the photo. Other important information is the called lithological mapping, which involves the interpretation of surface features so that can be obtained a more exact map. Gold particles can be deposited into fractures. When a fracture is observed in cross section, it seems to be vertical or near vertical breaks in the bedrock. Basically, there are four types of information, fracture and trace analysis, fracture identification, seep detection and channel change study. In general, photogeology involves the interpretation of an area’s geology from analysis of landforms, drainage and vegetation. The typical aerial photos are those which are taken with the camera lens vertical due to oblique photos could exaggerate the relief. It is also good for determining moisture content of soils. This makes them useful for locating outcrops in highly vegetated areas. Also least affected by fog, and is effective in cloudy environment.
In color photos, the red areas indicate live vegetation. Films used include black & white, true color, and Infra-red. Images are recorded either on films or by recording the image digitally. It gives complete information of high altitude photography and satellite photography. Photogeology is a very important of gold deposit exploration. Perhaps, the most important techniques are photogeology and seismic techniques. With these methods, the geologist is looking for anomalies. Commonly more than one method is employed. Gold deposits are sought with many techniques, but they are based on geochemical studies. In turn, this is followed by detailed geophysical studies and later, a detailed drilling, sampling, assaying and mineralogical study. This is followed by reconnaissance exploration in which satellite remote sensing geological mapping and seismic techniques are used. The current technology is very important in development new project and exploration of new deposits begins with the selection of a target area. Samples can be obtained by drilling programs Gold is a very widely disseminated throughout nature and may be found in any geological formation from the oldest rocks to the deposits that are still being formed, but in common with other metals, it is more likely to be found in the oldest rocks and in those places where the earth crust has undergone the most extensive changes such as elevations, folding, tilting, faults, fissuring and also volcanic action, with resulting changes in the composition and texture of the rocks.
The large mining companies of the world are focused in big deposits and the small deposits are attractive for small miners and perhaps their interest for gold is the most valuable tool for exploring new deposits. There are several places with important content of precious metals waiting for skill prospectors. Prospecting and exploration that is a search for precious metals deposits is not a simple process because big deposits were discovered a long time ago.