Akaishizawa

...The steep slopes on the eastern side face the Fossa Magna lowlands, are bounded in the west by the Median Tectonic Line (Tsutetsuki Pass to Misakubo) and the Akaishi Fissure Line (Mizakubo to Futamata), and in the south, drop off toward the Tokai coast. The Akaishi Mountains are named after Akaishi-dake (formerly known as Ogawarano-dake, 3,120m), but Akaishi-dake is named after the red exposed bedrock and boulders in Akaishi-zawa, which carves the southeastern slope. These red bedrock and boulders are made of red slate layers containing basaltic lava and volcanic ash that were deposited on the Mesozoic seafloor, and sometimes contain radiolarian fossils.

*Some of the terminology that mentions "Akaishizawa" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…東側にある急斜面は，フォッサマグナ低地帯に臨み，西部は中央構造線(杖突峠～水窪（みさくぼ）)，赤石裂線(水窪～二俣)で限られ，南部は東海地方沿岸部に向かって低下している。赤石山脈の名称は赤石岳(旧称大河原ノ岳，3120m)に由来するが，赤石岳の名は，その南東側斜面を刻む赤石沢にある赤色の露出岩盤や転石にちなむ。この赤色岩盤･岩塊は，中生代の海底に堆積された玄武岩質溶岩や火山灰などを含む赤色板岩層からなり，時には放散虫化石を含む。…

※「赤石沢」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報