Many “strange” phenomena, such as seismic, electric, magnetic, or other ones related with geological evolution, have occurred in a zone covering 20°~40°N of the Earth. This zone, so called 30°N tectonic deformation zone, has been the most active part in deformation and is related to the interior stress field of the Earth. When the Earth, as a sphere (ignoring its irregularities), revolves on its own axis, stress concentration and transform significantly occur within two latitudinal zones:one covers 20°~40°N and one covers 20°~40°S. It is the stress concentration and transform that cause most of those “strange” phenomena mentioned above.