- Location: on the right bank of Que Son River, about 150m from Minh Long irrigational dam to the SE, Minh Long commune, Ha Lang District. Coordinates 22°49’61”N, 106°46’10”E.
- Description: The low part mainly consists of thin-bedded marlaceous shale, thin- banded, interbeds or lenses of clayish limestone, limestone. They all have a greenish gray, pale yellow when being weathered. Unconformably overlying layers are conglomerate, sandstone, interbeds of dark red shale.
- The uniqueness: this unconformity relation is very rare, characterizes of Caledonian Orogeny, a geological boundary has significant connotation for science and education.
- Conservation Status: Not yet protected. This geological heritage is located on the river bank, under the traffic roads so it is easily ruined
|Conglomerate of Song Cau series (left) overlain unconformity on marlaceous shale Than Sa formation (right).|