An obsolete term for that part of a geosyncline characterized both by sediments deposited in shallow water and by the absence of volcanics. In the classification of geosynclines, miogeosynclines had a relatively thin sedimentary pile and were developed closer to the craton than the volcanic eugeosyncline. The geosynclinal theory of the formation of orogenic belts has been superseded by various plate tectonic models, and the term ‘miogeosyncline’ has been replaced by ‘miogeocline’ which is a purely descriptive word having no connection with geosynclinal theory.