紀伊半島の土台をなす竜神付加体と、その上に堆積した前弧海盆堆積体の熊野層群の境界部が露出します。竜神付加体が堆積・付加した後、その上に熊野層群が堆積するまでには、5000万年の時間が経過しており、このような関係を傾斜不整合といいます。竜神付加体は、ジオパーク地域内最古の地層群で、恐竜がいた白亜紀に堆積しました。すぐ上流の河床には熊野層群の砂岩層中にポットホール（甌穴）がみられ貝化石もみられます。

The boundary between the Ryujin accretionary prism, which forms the basis of the Kii Peninsula, and the Kumano Group of forearc basin deposits deposited on it is exposed. After the Ryujin accretionary prism is deposited and added, 50 million years have passed before the Kumano Group is deposited on it, and this kind of relationship is called tilt inconsistency. The Ryujin accretionary prism is the oldest stratum in the Geopark area and was deposited in the Cretaceous period when dinosaurs lived. On the riverbed just upstream, potholes (potholes) can be seen in the sandstone formation of the Kumano Group, and fossil shells can also be seen.

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うえもり　う 2022/01/20(Thu) 17:03 No.144