Issues of geomorphology of the Yan-Shan Ridge in Northern China

Abstract

Geographical position. Yan-shan ridge is located in the northern part of He-pe province of Northern China. It is located between 40-41° of north latitude and 115-120° of east longitude. This ridge separates the plateau of Inner Mongolia from the North China Plain. The Great Wall of China was built along it in ancient times. Geologic structure. The orogeny that resulted in the folding of ancient sediments in various areas of China during the Upper Jurassic and Cretaceous was called the Yanshan orogeny. No orogeny earlier than the Yanshan folding is known in North China, except for a putative orogeny of pre-Xinian time. The Sinyi system basically corresponds to Upper Proterozoic. time. Beginning in the Sinaian, down to the Jurassic, sedimentary rocks were accumulated in parallel horizontal layers. The layers in this stratum lie more often in accordance with each other, but sometimes stratigraphic disagreement is observed. The disagreement is most pronounced between Ordovician limestones and various rocks of the Middle Carboniferous. This indicates that North China was a landmass during the Silurian and Devonian periods.