Posted by: tsubakuro | February 7, 2012

The Japan Alps – a cursory glance from above

As a mountaineer in the Japan Alps, you have probably scrutinized the maps and are well familiar with the routes to the famous peaks. If you are a diehard fan you might have gone as far as to memorize every ravine, ridge, and summit and can write the Kanji and cite the elevations of all the major peaks as well as many minors ones too. I love maps because I love to see how real-life geographical landscapes are prepared as a visual language on paper and to compare that flat 2D world of limited chromatic range to the living landscape.

I also love aerial and satellite images because they are offer a third perspective that bridges map with reality. In February, I intend to post three installments of satellite images pilfered from GoogleEarth – for educational purposes! – to share with the curious and interested views of the three ranges of the Japan Alps to add that additional perspective to your memory banks.

Today’s first installment is the Chuo (Central) Alps – 中央アルプス – and the Minami (South) Alps – 南アルプス, also known as the Kiso Range and Akaishi Range respectively (木曽山脈、赤石山脈).

The Chuo Alps / Kiso Range - 中央アルプス / 木曽山脈

First, please notice the orientation of the image. The North/South orientation of the range has been rotated so that the range fits in diagonally in the image frame. This was so I could fit the entire range in the image while getting as close as possible.

Major peaks are marked with a red asterisk, the one for Houkendake (宝剣岳) slightly more distant from the text than the others because of text space limitations. The Senjoujiki Cirque (千畳敷カール) is also marked. The two Hyakumeizan (百名山) are Kisokomagatake (木曽駒ヶ岳) and Utsugidake (空木岳).

The Chuo Alps is the smallest of the three ranges and is located entirely within Nagano Prefecture. The highest point is at Kisokomagatake – 2,956 metres.

The Minami Alps / Akaishi Range Northern Region - 南アルプス / 赤石山脈の北部

This image of the northern region of the Minami Alps has the major peaks marked with a red asterisk. The Hou-ou Sanzan (鳳凰三山) is comprised of (from NW to SE) Jizoudake (地蔵岳) where the famous granite spire The Obelisk stands, Kannondake (観音岳) the highest peak of the three at 2,840 metres, and Yakushidake (薬師岳) with its famous granite tors. Kitadake (北岳) is the highest peak in the range the the second highest in Japan. Recent measurements put it at 3,193 metres.

Minami Alps / Akaishi Range southern region - 南アルプス / 赤石山脈の南部

Due to the presence of cloud in the satellite image, the image quality here is a little foggy. The main peaks as well as notable neighbours are marked here. One glaring omission from the Minami Alps images is Shiomidake (塩見岳), which is north of this image and just south of the previous image. It seems I zoomed and saved too hastily to notice that this Hyakumeizan was cut out of both pictures.

Chuo Alps and Minami Alps with tectonic lines - 中央アルプス、南アルプスと糸魚川静岡構造線/中央構造線の一部

Here is the grand view including both the Chuo and Minami Alps. Several other geographical landmarks are marked, including Lake Suwa (諏訪湖), Fujisan, Kinpusan (金峰山) of the Kai Okutama Chichibu Mountains, the mountains of Yatsugatake (八ヶ岳), and the volcanoes of Ontakesan (御嶽山) and Norikuradake (乗鞍岳).

The red lines indicate the tectonic lines of the Itoigawa/Shizuoka Tectonic Line (main and right) and the Chuo Tectonic Line (left). The Itoigawa/Shizuoka Tectonic Line (糸魚川静岡構造線)drawn in by hand here by me, veers a little too far to the east. According to the map on Wikipedia, the line cuts in closer to the west. I had assumed the tectonic line followed the river as many of them do in Japan.

The Chuo Tectonic Line (中央構造) here is only shown where it cuts through the Tenryu River (天竜川)  Valley and separates the Chuo Alps from the Minami Alps. Looking at the map on Wikipedia, we can see the tectonic line cuts across much of the Japanese Archipelago.

One interesting consideration I have had concerning average elevation of the three ranges and the relationship to tectonic lines is that, in general, the Kita Alps have more mountains over 2,900 metres and their range (the range of the 2,900-metre plus peaks) covers a greater surface area than the Chuo and Minami Alps. The Chuo Alps have only two peaks over 2,900 metres (three including Nakadake of Kisokomagatake) and the range of 2,900-metre plus peaks in the Minami Alps is limited to the central range and does not extend to any flanking ranges as in the Kita Alps. Is this because the mountain building forces in the Kita Alps were concentrated along only one tectonic line – the Itoigawa/Shizuoka – while the forces were exerted over two tectonic lines in the south, hence the formation of two separate ranges? The Minami Alps cover the greatest surface area but are comprised of many lower mountains. Were it not for the Chuo Tectonic Line, would the Minami Alps have developed with more 2,900-metre plus peaks? Would they have sustained further glaciation than they have? Would there have been a “Minami Yari”?

Interesting enough to ponder, however one should keep in mind that the Minami Alps are said to both have been higher during the last glacial period and still rising as orogeny – the process of mountain building – does its work. Over the course of geologic time, the Minami Alps may well grow in higher.

All images from Google Earth. Colour slightly saturation slightly increased and geographic landmark names added by me. The images here are for educational purposes only.

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