Theory:

Archaeologists use many ways to look for lost cities or unknown places. Their goal while searching is to find clues. Some examples are bricks, stones, or pieces of broken items.
 
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They also do a photographs study, which can sometimes lead them to what's on or under the surface.
 
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Before excavating a site or marking a place for digging, archaeologists use a grid system to make a plan. The grid system is used to map out where to start a dig.
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They work in their squares, cleaning away the vegetation using steady and cautious movements. They always keep track of each finding. Documentation plays a significant role for them.