Probably even more than Megiddo, Jericho is one of the places where the modern science of archaeology was born.  Unfortunately, the initial archaeologist of the site was Garstang, and he removed everything as he went.  Things weren’t cataloged.  Extensive pictures weren’t taken.  The result is that the most important twenty feet of the Tel were removed. 


The tower that Garstang finally discovered, in the picture below, is now universally dated to about 7000 BC!  In short, he removed any hope of finding evidence for a city there during Joshua’s day.




However, Kathleen Kenyon invented good archaeology on the back of his failures.  In particular, the idea is to dig in squares where the sides of previous layers can be seen.  While you remove down to bedrock at some points, you leave some part of each layer standing.