Geomorphological-Tectonic geosite in the northern part of Cao Bang

− Thang Hen Lake consists of a chain of 7 connected lakes, formed by the collapse of the ceiling of the underground river cave (Figure VI.2.8).

− In the northern corner of Thang Hen Lake, there is a threaded cave helping to regulate the water level in the dry and flood season (Figure VI.2.19). There is also a candles-shaped tower overlaying on the conical foundation, including the falling rocks formed in the process of creating towers from flanks.

− Ranges of residual karst apex interleave with ancient erosional karst valleys, which are connected in Thang Hen area.

Figure VI.2.19. Connected Cave in Thang Hen Lake.