Geological genesis of Baishuiyang Geopark

Baishuiyang is a wide flat-bottomed bedrock river bed, and its formation is restricted by lithology, geological body occurrence, geological structure and hydrodynamic conditions. The syenite porphyry in Baishuiyang river bed was a volcanic activity about 90 million years ago, which was diffused by magma flowing near the surface and formed a plate-like subvolcanic rock parallel to rhyolite layer. Rock has the characteristics of good integrity and uniform and compact structure. Under the action of in-situ stress, dense parallel plane horizontal joints and vertical joints and cracks in northeast, northwest, north and south, east and west directions are produced.

Pliocene, about 5.3 million years ago, with the crustal uplift, valley undercutting, overlying strata denudation, syenite porphyry exposed to the surface, weathering and flowing water erosion slowly stripped along the near-horizontal joints. The flat-bottomed riverbed with syenite porphyry as its bedrock began to form. Subsequently, the crust began to rise slowly, and the riverbed was eroded mainly by downward shearing, supplemented by lateral erosion. The width and height of the riverbed decrease, forming a new undercut riverbed, and the bedrock riverbed on both banks gradually rises, forming terraces.

Since about 2.6 million years ago, the crustal activity has been relatively stable, and the Baishuiyang area has risen very slowly in a relatively stable state. The earth's crust rises almost as fast as running water. The flowing water is close to the local erosion datum, and the erosion kinetic energy of flowing water is low. The main erosion is to widen the riverbed, and syenite porphyry, rhyolite and ignimbrite weathered debris on both sides of the eroded riverbed are peeled off one after another. In addition, the scouring ability of water flow is greater than its flow and the catchment area of two rivers. With the increase of flow, the lateral scouring ability of water flow is improved. At the junction of the two rivers and its upstream and downstream, the strong lateral erosion of water flow formed a wide arc-shaped concave bank. After long-term erosion and lateral erosion by flowing water, the riverbed extends longitudinally and transversely along the slab syenite porphyry, forming a flat-bottomed bedrock riverbed smooth as a mirror. White waves are sky-high, and the sparkling ocean of white waves is ankle-deep. It is an extremely rare shallow-water flat-bottomed bedrock river.

Baishuiyang has been in a relatively stable tectonic activity period for a long time. Long-term lateral erosion and abrasion make the valley erosion expand into a wide flat-bottomed bedrock riverbed, and the valley becomes "shallow water". This relic is of great significance to the study of volcanic petrology, fluid mechanics, structural geology, hydrogeology and other disciplines.