熊本県内には様々な地層や岩体が分布する。例えば、球磨山地の黒瀬川帯には県内最古約4億2千万年前（古生代シルル紀）の化石を産出する地層があり、北部には約27万〜9万年前（新生代第四紀）の阿蘇火砕流堆積物が広く分布する。それらの地層には遠洋で堆積したものや、大陸棚、或いは陸上で堆積したものがある。球磨川の河床に露出する海生厚歯二枚貝メガロドンの化石は、はるか南方にあった火山島がプレート運動にともなって北上し、この場所に到達したことを物語る。一方球磨山地や天草諸島に分布する中生代白亜紀〜新生代古第三紀層は大陸棚〜陸上の環境で堆積した地層であり、恐竜を含む多様な化石を産出する。

Kumamoto prefecture is composed of a large variety of formations and rocks ranging from the Paleozoic Silurian period to the Tertiary Cenozoic period. All those formations are distributed all around Kumamoto prefecture and you can for example find Kumamoto’s oldest formation in Kuma mountain’s Kurosegawa zone (Silurian, -420MY) or have a look to Aso pyroclastic flows (Cenozoic, -0.27MY ~ -0.9MY) in the northern part of the prefecture.

As those formations were formed in different environment such as oceans, continental shelf or land, all kind of fossils can be observed. such as:

-       Kumagawa riverbed’s marine rudist fossils called Megalodon, which fossilized in more southern islands and were pushed north to Kumamoto because of the plate tectonics.

-       Kuma mountain and Amakusa archipelago’s Cretaceous ~ Paleogene layers which were formed on a continental shelf in a continental environment and which contain a lot of fossils such as dinosaur bones.