Annex 2
Separate Print of Chapter B (The Earth’s Geological Heritage) in the
Application Dossier for Nomination to the Global Geoparks Network

Mt. Apoi Geopark – Japan
Summary
Mt. Apoi Geopark is located near the southern tip of Hokkaido, which is thenorthernmost island of the Japanese Archipelago. Mt. Apoi is 810 meters high andlocated at the southwestern end of the Hidaka Mountains, which are known as the
backbone of Hokkaido.
The most distinctive feature of Mt. Apoi Geopark is the mountain’s peridotites,
which derive from the earth’s mantle. They are visible above ground because part of theupper mantle containing them, which is further beneath the crust, was pushed onto theearth’s surface by a collision of crustal plates. These rocks form part of Mt. Apoi as acomplex. Man has of course never set foot on the mantle because it is located deep
under the earth’s surface. However, Mt. Apoi Geopark provides visitors with a window
into the interior of the earth, allowing them to feel global-scale dynamic ground motion.
This motion has produced unique and valuable colonies of alpine flora on Mt. Apoi,
fascinating climbers from across Japan. The area’s geological heritage has alsosignificantly affected the daily lives of local residents.
Chapter B describes the geological heritage of Mt. Apoi Geopark, including its
peridotites, as well as the resulting ecosystem and cultural history.

Mt.Apoi Geopark,

Japan

B.

Geological Heritage

B-1.

General geological description of the proposed Geopark

B-1-1.

Geological position and background

Hokkaido is the northernmost island of Japan, and is located between the Pacific Ocean and the AsianContinent. The Hidaka Mountains in the central axial region of Hokkaido are characterized by
2,000-meter peaks, running from north to south, forming the island’s backbone, and dividing into
eastern and western Hokkaido. As shown in Fig. B-1, Mt. Apoi (altitude: 810.2 m; 42° 06’ 28’’ N, 143°
01’ 31’’ E) lies at the southern end of the
Hidaka Mountains, facing the Pacific
Ocean.
Looking at Hokkaido from the ocean
floor of the Pacific, there are steep
escarpments off of the Kuril Islands andNorthern Honshu. The Kuril Trench(running from Kamchatka to eastern
Hokkaido) intersects with the Japan
Trench (running further southward fromwestern
Hokkaido
to
Honshu).
Geographically speaking, this is the sitewhere the Kuril arc is merging with the Fig. B-1 Topographical map around Hokkaido and Mt. Apoi
Honshu arc.
(courtesy: Google Earth)As shown in Fig. B-2, Hokkaido is located at a triple junction of three major plates covering theearth’s Northern Hemisphere: the Pacific Plate, the North
American Plate, and the Eurasian Plate. This section highlights
the location of Mt. Apoi Geopark in relation to these plates. The
Pacific Plate subducts to the northwest beneath the Japanesearchipelago at the northwestern margin of the Pacific Ocean. The
subduction rate is approximately 10 centimeters a year. As
clearly shown in the map of Fig. B-1, Hokkaido was located at
the boundary between the North American Plate and theEurasian Plate, both of which stayed above the subduction slabof the Pacific Plate, at the beginning stage of the Hidaka
Mountains building.
Figure B-3 (map of the Northern Hemisphere) shows anarrangement of these three major plates on a global scale. The Fig. B-2 Map showing relationship of 3
plates in areas near Hokkaido, at
northern extension of the plate boundary between the North major
the beginning stage of the Hidaka
American and the Eurasian plates can be traced to the Atlantic mountain building (Niida, 1999). Mt. Apoi
Ocean, on the other side of the globe. Here, successive was located at the southwestern marginof the North American Plate, colliding onsubmarine volcanic activity along the axis of the Mid-Atlantic the Eurasian plates.
Ridge creates an oceanic lithosphere (comprising the crust to theuppermost mantle) of the Atlantic Ocean floor. The average spreading rate is 2~3 centimeters a year
on one side, which has continued steadily since the end of the Jurassic Period, when the seafloor
spreading began to form the Atlantic Ocean.
As shown in Figure B-3, the divergent plate boundary of the Mid-Atlantic Ridge continues
northward to the Arctic Ocean near the North Pole. The sense of divergence in plate motion changes
into a convergent boundary, near the North Pole onward. In the area surrounding Hokkaido, the plateboundary between the two plates is located at the eastern margin of the Sea of Japan (thick solid line).
At the present stage, the Eurasian Plate is considered to have begun a new subduction eastward
beneath Hokkaido along the boundary. The other boundary along the central axial zone of Hokkaido-8-

Mt.Apoi Geopark,Japan(thick broken line in Fig. B-3) was there when the Hidaka Mountains started lifting up, 13 million
years ago. Then, the western margin of the North American Plate is thought to have been thrust onto
the Eurasian Plate to the west, resulting in the formation of the mountains.
B-1-2.

Geological Overview

This section outlines the geological characteristics of Mt. Apoi Geopark and the surrounding area. The
Hidaka Main Thrust (HMT) extends along the western foot of the Hidaka Mountains in the central partof Fig. B-4. The eastern and the western areas of the HMT have completely different geologicalfeatures. Metamorphic and plutonic rocks are observed in the Hidaka Metamorphic Belt, covering the
Hidaka Mountains to the east, while the western area is characterized by the Cretaceous fore-arc basin
sedimentary rock and the accretionary complexes that formed on trench slopes from the late
Cretaceous to the Paleogene period.
The HMT can be recognized as a global-scale mobile belt of the Earth. The location corresponds
to the convergent plate boundary shown by the thick broken line over central Hokkaido in Fig. B-3(map of the Northern Hemisphere). Therefore, Mt. Apoi Geopark is a showcase which is composed of
two distinct geological formations that were created in different places of the different plates. Mt.Apoi
Geopark gives an opportunity to experience the outcome of global-scale motion of the Earth forvisitors.

Fig. B-3 Map of the Northern Hemisphere of the Earth,showing the relationship between of the Northern American andEurasian plates. (Niida, 2010). The thick solid line shows thepresent boundary between the Northern American and Eurasianplates. The thick broken line running along the central axial
zone of Hokkaido indicates the plate boundary at the Hidaka
mountains building stage (late Miocene). See Fig. B-2.

Fig. B-4 Simplified geological map of
Mt. Apoi Geopark and the surroundingarea, showing major geological units.
Referred from the Seamless Digital
Geological Map of Japan 1:200,000:
Hokkaido (Geological Survey of Japan,
2003).

(1) Geological features of the Hidaka Mountains and local rocks
The Hidaka Metamorphic Belt extends from the Hidaka Main Thrust (HMT) to the eastern foot of the
Hidaka Mountains as shown in Fig. B-4 (geological map). The Horoman peridotites derived from theupper mantle are exposed on the earth’s surface at the base of the metamorphic belt, and are overlaid
with a sequence of geological formations formed within the deep-seated Earth's crust to the east. These
are granulites and amphibolite (high-grade metamorphic rocks representing the lower crust), biotite
gneiss and biotite schist (representing the middle crust) and schistose hornfels and other hornfels(representing the upper crust). Large masses of gabbro that solidified in basaltic magma chambers in-9-

Mt.Apoi Geopark,Japanthe lower crust are exposed on thewestern side of the Hidaka Mountains,and diorite and granite that formed inmagma chambers in the shallow crust
are exposed from the eastern side to thefoot of the mountain range. The
east-west geological cross-section of the
Hidaka Mountains is shown in Figure
B-5, indicating the most representative
metamorphic and plutonic rock types inthe Hidaka Mountains, as well as
geological structures dipping eastward.
This section highlights two valuablerock specimens collected from the Fig. B-5 Geological cross-section of the Hidaka Mountains
Hidaka Mountains. The first is (Niida, 1997). HMT: Hidaka Main Thrust. This profile shows asequence of the most representative metamorphic
granulites, which is a high-grade geologicaland plutonic rock types, which are typically observed in E-W
metamorphic rock representing the traverse of the Hidaka mountain range. All the geological piles
lowermost crust (Fig. B-6). Granulites are dipping eastward.
are primarily composed of garnet,
orthopyroxene, cordierite and plagioclase, and the estimated equilibrium temperature and pressure
based on geothermobarometry are T = 800°C and P = 7.5 kbar (Osanai, 1985). The other is sillimanite
tonalite (Fig. B-7), which was crystallized from tonalitic magmas injected into biotite gneiss in the
middle crust, containing large crystals of sillimanite.
Extensive research has been conducted to determine the age of the metamorphic and the igneousrocks by using radioactive isotopes. The Hidaka Metamorphic Belt is known as an extremely young
formation based on the age determination indicating between 55 and 17 million years ago (from early
Paleogene to middle Miocene) (The Geological Society of Japan, 2010).

Fig. B-6 Granulite from the upper Horobetsu River,composed of garnet, orthopyroxene, cordierite andplagioclase. This represents a high ‐ grade
metamorphic rock from the lowermost crust.

Fig. B-7 Sillimanite tonalite from the beach at
Chipira, containing columnar megacrysts ofsillimanite. This represents a typical rock forming
the middle crust of an active island arcs.

The temperature-pressure chart of Fig. B-8 plots the estimated equilibrium temperature andpressure for typical metamorphic rocks, such as granulites, amphibolite, biotite gneiss, schist andhornfels, obtained from the Hidaka Mountains (Osanai, 1985). The thick broken line shows ageothermal gradient (i.e., the rate of temperature increase with depth) during metamorphism within the
Earth's crust. The highest geothermal gradient of metamorphic rock in the Hidaka Mountains isapproximately 34°C/km as clearly shown in Fig. B-8. This is identical to that of the undergroundtemperature gradient beneath the central axial ranges of an island arc with ongoing volcanic activity
such as the Japanese island arc. Geothermal gradients of around 30°C/km are not as high as thoseobserved in mid-ocean ridges, but are substantially higher than continental gradients (approx.
10°C/km) and oceanic island gradients (approx. 15°C/km).
The Hidaka Mountains are made up of geological units formed at the deeper interior of an island
arc lithosphere. They are scientifically and educationally significant because they provide a visual- 10 -

Mt.Apoi Geopark,Japan

representation of deep-seated lithospheric geology of avery active island arc. In the Hidaka Arc as shown in Fig.
B-8, granulites and amphibolite in the lowermost crust
partially melted when the underground temperature
exceeded approximately 850°C, which is a melting point
for felsic tonalite magma. In the Japanese archipelago andother tectonically active island arcs, metamorphic rockbelow 25 kilometers underground is heated totemperatures above the melting curve, causing melt
generation. Here we can consider melting events
generating in an active lower crust of an arc such as Japan.
In the Hidaka Mountains, regularly stratified
geological formations are well preserved from the upper
mantle to the shallow crust, where these metamorphic andigneous rocks formed. As a result, the geological eventof magma generation beneath the island arc is possibly
explained as shown in a reconstruction model of the
Hidaka Mountains (Fig. B-9). In the Hidaka Mountains,
the representative types of metamorphic and igneousrocks can be observed in outcrops on the earth’s
surface, providing outstanding opportunities for people
to understand the depths of an island arc lithosphere.

Fig. B-8 Temperature-pressure chart formetamorphic rocks from the Hidaka
Mountains (Niida, 1999), showing a highgeothermal gradient (approximately 34°C/
km).

(2) Geology of the western mountains foot to thecoastal areas
The sedimentary rocks, observed in the areas from thefoot of the Hidaka Mountains west of the Hidaka Main
Fig. B-9 Reconstruction model for generations
Thrust (HMT) to the coastal areas, are originated fromof the Hidaka metamorphic and igneous rocks(Niida, 1999), showing a spatial distribution of
the Cretaceous arc-trench systems (i.e., those in the
representative rock types. This corresponds toCretaceous fore-arc basin area, and the late Cretaceousthose in the geological cross-section (Fig. B-5).
to Paleogene accretionary complex area). This geology
differs significantly from that of the Hidaka Metamorphic Belt, which includes metamorphic andplutonic rocks. The ages of the rocks are also different (The Geological Society of Japan, 2010).
Accordingly, it is stressed that Mt. Apoi Geopark is a showcase of a level of geodiversity that clearly
represents a typical arc-trench system.
(a) Cretaceous system (fore-arc basin area)
As shown in the geological map (Fig. B-4), sedimentary rocks(e.g., sandstone, mudstone, and their alternations) thatoriginated in the Cretaceous fore-arc basin are distributed in
the coastal area from Urakawa Town to Samani Town aroundthe lower streams of the Horobetsu and the Samani rivers. The
Cretaceous system in this region often corresponds to the Yezo
Group (mostly to the Middle Yezo Group distributed along thecentral axial part of Hokkaido). In part of the region (i.e., thatin the northwestern area of the figure), the Lower Yezo Group Fig. B-10 Alternating sandstone andand the Sorachi Group are also distributed on a smaller scale. mudstone layers (Middle Yezo Group)
behind Samani Elementary School.
These areas belong to the southernmost region of the
Sorachi-Yezo Belt in the tectonic division for Cretaceous systems in Hokkaido (The GeologicalSociety of Japan, 2010).
(b) Upper Cretaceous – Paleogene System (accretionary complex area)
The late Cretaceous to Paleogene accretionary complex is distributed in areas across the middle to theupper streams of Horobetsu and Samani rivers in the foot of the Hidaka Mountains. The complex was- 11 -

Mt.Apoi Geopark,Japan

formed from the late Cretaceous to the early Paleogene in the accretionary prisms near the trench slopeof the Cretaceous arc-trench system. They consist mostly of sandstone and mudstone, and also include
a large number of blocks of limestone, chert, basaltic pillow lava, and other types of greenstones
everywhere. The rocks vary in size from gigantic (several hundred meters) to small (several
centimeters), and are incorporated within a matrix of sandstone and mudstone. The blocks are exotic,
having older ages from the Triassic to the Jurassic Period, and are considered to have formed inseamounts and oceanic islands on an old oceanic plate (The Geological Society of Japan, 2010). The
Upper Cretaceous to Paleogene systems are also extensively distributed in areas to the northeast of the
Hidaka Metamorphic Belt, and are characterized by transition to hornfels of the Hidaka Metamorphic
Belt in the area shown by the broken line in Fig. B-4.
(c) Neogene System (sedimentary rocks and porphyrite dykes)
Neogene sedimentary rocks and porphyrite dykes are distributed in a limited small area of the coastal
region, which is a residential area of Mt. Apoi Geopark. The
sedimentary rocks are composed primarily of conglomerate,
sandstone, and mudstone, containing shell fossils fromshallow-sea habitats. The porphyrite dykes are observed insandstones and mudstones in the Cretaceous System (thefore-arc basin area), forming a beautiful landscape of oddly
shaped rocks along the Samani coast. As the porphyrite dykes
at Mt. Kannon, Shiogama Tunnel, Rosoku-iwa, Oyako-iwa,
Sobira-iwa, and Cape Enrumu are harder than the surrounding
Fig. B-11
A distinctive coastal
sedimentary host rocks, it forms landscapes of oddly shaped landscape of Mt. Apoi Geopark formedby porphyrite dykes.
masses unaffected by coastal erosions.

(3)

Terraces at the foot of Mt. Apoi (Samani – Horoman coasts)

Fig. B-12 Marine terraces observed in coastal areas from the Samani coast to the Horoman coast at
the southern foot of Mt. Apoi. (Terrace surfaces t1 – t4: after Kanie and Sakai (2002)).

Remarkable terraces can be observed from the Samani
coast to the Horoman coast at the southwestern foot of Mt.
Apoi. Figure B-12 is a view of Mt. Apoi from Cape
Enrumu; flat coastal terraces can be seen at the foot of themountain. The 1:50,000 Geological Map of Horoizumi
shows four planes with the highest at an elevation over
300 meters and the lowest at 20 meters. The presence ofmarine terrace deposits consisting of gravel, sand and clay
has been confirmed in the area (Hunahashi and Igi, 1956).
The coastal terraces located in the area from the Samani
coast to the Horoman coast were also examined in anarticle by Ouchi (1978) on the history of terrace
development in areas near the Hidaka Mountains.

Fig. B-13 Terrace deposits covering the rockat Geosite D-1, Fuyushima’s Ana-iwa. The
yellow arrow points to pebble layers.

The terraces at the foot of the mountain, particularly in one of Samani’s residential areas, areconsidered an important geological feature directly related to the natural environment involving local- 12 -

Mt.Apoi Geopark,Japanhuman and pre-human history. Accordingly, it is necessary to understand aspects of naturalenvironmental transition closely related to local life, such as ground movement caused by an uplift of
the Hidaka Mountains, which is a phenomenon that continued until relatively recently in geologicalterms, sea level changes brought by the cycle of glacial and interglacial periods, and relationships withthe glacial landform of the Hidaka Mountains. Research is scheduled at locations of low terrace
deposits less than 20 meters in height or less, such as at several sea cliffs located in the residential areaof Mt. Apoi Geopark, as shown in Fig. B-13.
B-1-3. Outline of the Horoman Peridotite Complex
Peridotites are distributed along the Hidaka Main Thrust (HMT) of the Hidaka Mountains. The
Horoman peridotite forms the largest complex, and similar masses of the Uenzaru, Pankenushi,
Menashunbetsu, Nikanbetsu complexes are exposed. Small complexes are also known on the earth’s
surface in the middle of Pon-Nikanbetsu River and Abeyaki River. The complexes are bounded byfaults in contact with high-grade metamorphic rocks and overlain by various kinds of metamorphic
and plutonic rocks. All the peridotite complexes in the Hidaka Mountains have layered structures
composed of a variety of peridotite types derived from the upper mantle 60 to 70 km deep from the
Earth's surface (Niida, 2010).
(1) Peridotite types with three different origins
The Horoman peridotites are divided into three peridotite suites (Main Harzburgite-Lherzolite(MHL), Spinel-rich Dunite-Wehrlit (SDW), and Banded Dunite-Harzburgite (BDH)) based on themodal and chemical compositions of the minerals (Takahashi, 1991). These are considered to havebeen derived from the upper-mantle with individually three different origins (Niida, 2010).
(a) MHL suiteThis peridotite suite is composed primarily of harzburgite, spinel lherzolite and plagioclase lherzolite,
which occupies the majority of the Horoman complex (over 90% of the complex). Detailed studies of
their whole-rock chemistry and chemical composition of the constituent minerals, such as olivine,orthopyroxene, clinopyroxene, and spinel, have been carried out. Basaltic melt components gradually
decrease and the degrees of partial melting increase from plagioclase lherzolite through spinellherzolite and to harzburgite. These characteristics in compositional change indicate that the MHL
suite represents peridotites from the solid upper mantle with varying degrees of depletion of basaltic
magma, from fertile undepleted plagioclase lherzolite to extremely depleted residual harzburgite.

Fig. B-14 Four typical peridotite types of the
Horoman complex

Fig. B-15 Pressure-temperature path, showing
ascent history of the Horoman peridotite complex(Ozawa, 2004).

(b) SDW suiteThis peridotite suite is mostly of spinel dunite containing clinopyroxene. Small amounts of wehrlitic
peridotites are also found. It is characterized by a large number of idiomorphic spinel grains, and theperidotites are believed to be cumulates formed by the accumulation of crystals from basaltic magma
based on the characteristic chemical composition of olivine and spinel.
- 13 -

Mt.Apoi Geopark,Japan(c) BDH suiteThis peridotite suite includes harzburgite and olivine pyroxenite, and is characterized by absence ofclinopyroxene. Characteristically, extremely high-Cr spinel and extremely high-Mg olivine arecontained in this peridotite suite. Therefore, the BDH peridotite suite has been explained as cumulate
crystallized from boninite and/or high-Mg andesite magmas.
(2) Magma channels in peridotite
Mafic rocks are found in various sizes in the Horoman peridotite complex. The mafic rock Type I (GBI) and Type II (GB II) have similar rare earth element (REE) contents and isotopic compositions withthose of the Mid-Ocean Ridge Basalt (MORB). Harzburgite in the lower zone of the complex isaccompanied by numerous numbers of dunite dykes. The dunite dykes have also attracted attention as
rocks in magma channels that were formed by an ascent and migration of basaltic magma through theupper mantle peridotites (i.e., rocks crystallized in basaltic magma channels), as shown in the upper
left-photo of Fig. B-14.
(3) Ascent history of the Horoman peridotite complex
The earliest ascent of the MHL suite in the Horoman peridotite complex is examined as the deepest
record on pressure and temperature conditions of the upper mantle. The conditions of the garnet
lherzolite stability field is clearly shown by symplectites with an external shape of euhedral garnet
contained in orthopyroxene porphyroclasts within spinel lherzolite in the lower zone of the complex.
Reddish-purple fine-grained aggregate layers (sp+opx+cpx) containing symplectites are also found inlherzolite, and are considered to be products of decompressional garnet breakdown. Detailed studies
on pressure and temperature of the Horoman peridotites have been carried out, based on thecompositional zoning of Al2O3 in orthopyroxene and clinopyroxene porphyroclasts and thecompositional change of Al (cation) and Wo (mol. %). As shown in Fig. B-15, the ascent history
indicates that the temperatures recorded in the upper zone of the complex are approximately 200°C
higher than those in the lower zone, and that the maximum pressure is at least P = 20 kbar.
Accordingly, the Horoman peridotite complex is considered to have been up-lifted from a depth
greater than 60 km in the upper mantle.
(4) Age of the Horoman peridotites
The formation age of the Horoman peridotites is still an
on-going subject, providing scientifically important
information on the Earth’s history (Niida, 2010). Althoughpreviously published ages are only a part of such endeavors,
the Sm-Nd whole-rock isochron age determined from Light
Rare Earth Element (LREE)-depleted plagioclase lherzoliteand spinel lherzolite is 833±78 Ma (Fig. B-16). Likewise,
the age determined from pyroxenes is 1.15 Ga (1.15 billion
years). These ages are interpreted as those when the
Horoman peridotites remained after major partial melting
in the upper mantle beneath the mid-ocean ridge. Studies
on 187Os/188Os -187Re/188Os whole-rock isochron of
B-16 Nd-Sm isochrons showing age
peridotites and mafic rocks have reported apparent ages of Fig.
of the Horoman peridotites (Yoshikawa
0.91±0.35 Ga (approx. 900 million years) and 1.12±0.24 and Nakamura, 2000).
Ga (approx. 1.1 billion years).
The presence of numerous veins of phlogopite in peridotites in the lower zone of the Horomanperidotite complex has been widely reported, and suggests that a compositional modification took
place during the final stage of up-lifting from the upper mantle. The Rb-Sr isochron age (23.0±1.2 Ma)
and 40Ar-39Ar plateau age (20.6±0.5 Ma) obtained from the veined peridotites indicate an age justbefore the building of the Hidaka Mountains.

- 14 -

Mt.Apoi Geopark,

B-2.

Japan

Listing and description of geological sites within the proposed Geopark

Mt. Apoi Geopark has 35 geosites in 5 areas labeled from A to E (Fig. B-17). The geopark ischaracterized by the closely related themes outlined below. It is hoped that it will eventually lead tothe revitalization of local communities through the establishment of self-sustaining symbiosis between
nature and people.
Main theme:
A Story of Gifts from Deep Inside the Earth Connecting Land and People Together
Theme A: Peridotites – the interior and dynamic movement of the earth
Theme B: Alpine Plants – scarcity and the natural environment
Theme C: Human History – the community of nature and human life

As the individual characteristics of Mt. Apoi Geopark’s 5 areas and 35 geosites have meaningfulconnections with the three themes, visits should ideally be planned with individual objectives in mind
(e.g., research, geological field trips, hiking or scenic tours). This section highlights characteristics andtypical geological sites of each area. For a complete list of geosites, see Appendix 2 (“Mt. Apoi
Geopark Geosite List”).

Fig. B-17

B-2-1.

Mt.Apoi Geopark map

Area A Horomankyo Area : A gorge of peridotites

The peridotite Horomankyo Gorge is located in the lower and middle basins of the Horoman River,which runs from north to south over the central Horoman peridotite complex. It is a well-known site
for peridotite viewing.
Geosite A3.
Japanese White Pine Monument(Typical lherzolite)
This riverside monument marks a habitat of Horoman Japanese white pines – a Natural Monument ofJapan. The area is a type locality for lherzolite, which is a representative peridotite type known for its
significant amounts of pyroxene: thin reddish-purple fine-grainedmineral layers containing spinel-pyroxene symplectites (one toseveral millimeters in diameter) formed during decompressional
garnet breakdown. The lherzolite here provides informations on the
deepest part (approx. 60 – 70 km below the surface) of the mantle
from which the Horoman peridotite derives.
- 15 -

Mt.Apoi Geopark,Japan

Geosite A6.
Horoman-gawa Inari Shrine(Typical plagioclase lherzolite and mafic rocks)
Peridotites containing plagioclase and mafic rocks (Type GB I)
several centimeters thick are observed on the riverbank 200 meters
upstream of Inari Shrine. The plagioclase lherzolite has a highcontent of orthopyroxene (dark brown) and clinopyroxene (darkgreen), and its streaky white parts contain plagioclase. The peridotite
here is considered to be free from partial melting of basaltic magma in the upper mantle, and is typicalof the primitive mantle in terms of chemical composition. The outcrops here have large numbers ofcylindrical potholes often found by rapid streams, creating a distinctive landscape.

B-2-2.

Area B

Mt. Apoi Area : A mountaineering route showcasing the scale of local

peridotites
Mt. Apoi’s terrain is characterized by layered peridotite and gabbroic mafic rocks. The layers are
believed to have formed when mantle peridotite under high temperature conditions flowed or partiallymelted to become magma.
Geosite B5.
Umanose flower fields(Alpine plants and fine views)
The western ridge of Mt. Apoi, known as Umanose (meaning“horse’s back” in Japanese) has an altitude of around 580 meters.
Colorful alpine plants influenced by peridotites are found along thetrail from Umanose to the mountaintop. This location affords
sweeping views of the ridge extending from the top of Mt. Apoi tothe peak of Mt. Pinneshiri to the east, the backbone of the Hidaka
Mountains to the north, and the Pacific Ocean to the south. These
are splendid sights of the Hidaka Mountains and Mt. Apoi, whichwere formed by a collision of tectonic plates.
Geosite B8.
Mt.Apoi to Mt.Yoshida(The upper zone of the Horoman peridotite complex)
This geosite is characterized by a route along the northern ridge
extending from the top of Mt. Apoi to the peak of Mt. Pinneshiri.
The peridotites in this area are part of the uppermost zone of the
Horoman complex, which is around 3,000 meters thick, andperidotites with a conspicuous layering of plagioclase lherzolite and mafic rocks are observed.
B-2-3.

Area C

Samani Coast Area : Landscapes of Cretaceous sedimentary strata

and intrusive rock
The hilly terrain to the west of Mt. Apoi is characterized by Cretaceous fore-arc basin sedimentaryrock (e.g., sandstone and mudstone), while Neogene sedimentary rock and porphyrite form the coastalarea’s unique landscape. Visitors can learn about the geological narratives hidden behind the area’s
different landscapes.
Geosite C1 –C 4.
Cape Enrumu, Oyako-iwa and other oddly shaped rocks(Porphyrite and dykes)
From Cape Enrumu to Shiogama and Fuyuni in the west, porphyrite
dykes running through the surrounding Cretaceous sedimentaryrocks has resulted in the presence of several large rocks along theshore. Magmatic intrusion occurred around 17 million years ago (inMiocene), and the current shapes were formed by coastal erosion.
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Mt.Apoi Geopark,Japan

The wave-cut platforms that appear around the rocks at low tide teem with marine life. Magnificent
platy joints are also found at the cliffs behind Cape Enrumu.
Geosite C7.
Old quarry behind Samani Elementary School (Fore-arc basin sediments)
Sandstone and mudstone strata that formed in a Cretaceous fore-arc
basin around 100 million years ago are observed at the old quarry
behind Samani Elementary School. The hilly terrain in the western
half of Mt. Apoi Geopark consists of sedimentary rock from thisperiod and provides contrast with the Apoi Mountains to the east (i.e.,the Hidaka Metamorphic Belt).
B-2-4.

Area D

Hidaka Yabakei Area : A tectonic plate collision site

Hidaka Yabakei is a 6-kilometer stretch of rugged coast with cliffs running from Ana-iwa rock inFuyushima to the mouth of the Horoman River at the southern foot of Mt. Apoi. It is located at the oldboundary between the Eurasian Plate and the North American Plate.
Geosite D1.
Ana-iwa in Fuyushima (Hornfels and marine terrace)
Ana-iwa is a large rock with a hole running through it in Fuyushima
Fishing Port. The place name Fuyushima derives from the Ainu terms
puyo (hole) and shuma (stone). The hole is a sea cave through whichsurf boats traveled at high tide before the fishing port was built there.
The rock is mostly of fine-grained sedimentary rock, but biotite
formed when it was exposed to high temperatures deep in the earth
and then metamorphosed into hornfels. Terrace deposits are found on
top of Ana-iwa, and a small-scale coastal terrace is also located to its
east.
Geosite D2

Fault at the Higashi Fuyushima Tunnel(Serpentinite and metagabbro, and a convergent plate boundary)This geosite is a fault fracture zone by a national highway.
Metagabbro (in the Poroshiri Ophiolite Belt) is in the southwesternpart of the outcrop, and fractured serpentinite can be seen in the upper
part of its northern outcrop. The contact boundary between theserocks forms part of the Hidaka Main Thrust (HMT), and is consideredpart of the convergent plate boundary between the North American Plate and the Eurasian Plate.
Geosite D5.
Geological fold at the Ruranbetsu Tunnel(Hidaka Metamorphic Belt, amphibolite, biotite gneiss and terrace deposits)
In this rocky tract located at arock shed, folded biotite gneiss
and amphibolite of the Hidaka
Metamorphic Belt can beobserved. Amphibolite is ametamorphosed basaltic rock thatoriginated on an old oceanic plate.
Biotitegneissisrockmetamorphosed from terrigenous
clastic sandstone and mudstone. These metamorphosed rocks are considered to have been derived
from an accretionary prism that formed between the latest Cretaceous to the early Paleogene, and thenmetamorphosed. This geosite affords distant views of terrace deposits on the 100-meter-high sea cliffs,
thereby highlighting the area’s ground uplift.
- 17 -

Mt.Apoi Geopark,B-2-5.

Area EJapan

Shintomi Area : Rocks from far-off southern seas

The Shintomi Area is characterized by rocks formed at a Cretaceous accretionary prism, such as
limestone and chert. The accretionary prism is formed from the surface layer of oceanic plate that isaccreted onto a continental plate. Limestone, chert, and basalt derived from southern oceans,thousands of kilometers away, are mixed with terrigenous clastic sandstone and mudstone, forming a
mixture of different rocks known as a mélange. This site is at the southern end of the Idonnappu Belt,
which extends from south to north along the central axial zone of Hokkaido.
Geosite E1.
Old mine of Ono Kogyo Co., Ltd.
(Limestone, an accretionary mélange complex)
This geosite features an outcrop at an old quarry located behind alimestone processing plant. A mélange with blocks of limestone
surrounded by sandstone and mudstone can be observed. Prior
approval is needed to access to this geosite.
Geosite E2.
Lenticular sandstone at the Samani Dam(Sandstone and mudstone, an accretionary mélange complex)
An outcrop of mudstone and sandstone observed along the roadtoward the Samani Dam parking lot. A typical mélange structure canbe seen here, and lenticular sandstone without continuous bedding isobserved in the mudstone bed.
Geosite E3.
Chert in Shintomi(Chert, an accretionary mélange complex)
Translucent gray chert is found along the road near the confluence of
the Samani River and the Menashiesanbetsu River. Chert is denseand hard, and is composed mainly of very fine-grained quartz.

B-3. Details on the interest of these sites in terms of their international,
national, regional or local value
B-3-1.

A Global scale mobile belt

As shown in B-1-1, the geology of Mt. Apoi Geopark and the surrounding area results from global
scale dynamic ground motion.
One of the largest global-scale mobile belts in the world is the Tethyan ophiolite belt, extending
from the European Alps to Greece, Turkey, Iran, Oman, Pakistan, Indus Suture, Andaman, and theGreat Sunda. Here, the Alps mountain ranges were formed by a well-documented collision between
the African and the Eurasian continents, and the collision of the Indian continent and the Asian
continent generated to the uplift of the Himalayas. The Hidaka Mountains in Hokkaido were also
formed in a large mobile belt that divides the Northern Hemisphere almost vertically. The mountainbuilding was a global-scale geological event that took place at a convergent boundary between the
North American and the Eurasian plates. This suggests that the heavy peridotites located in the upper
mantle were up-lifted onto the earth’s surface from the depths of the North American Plate, thereby
forming Mt. Apoi.
B-3-2. Global significance of the Hidaka Mountains
The most attractive geological features of the Hidaka Mountains are summarized in the recent
monograph on "Geology of Japan" volume 1: Hokkaido (edited by the Geological Society of Japan, in- 18 -

Mt.Apoi Geopark,Japan2010). The following four characteristic aspects are mostly based on Chapter 1 Outline of Hokkaido(Niida, 2010) and Chapter 4 Geology and rocks in the Hidaka Collision Zone (Hidaka Mountains)(Osanai et al., 2010)
1. Hidaka Mountains are composed of rocks derived from the deep-seated lithosphere beneath anactive island arc.
2. The rocks are stratified in an original succession generated from the upper mantle to theshallow crust.
3. Such a regular sequence of lithospheric sections observed on the Earth's surface is very rare in theworld.
4. The age is extremely young (55~17 Ma in Cenozoic). The original state of the rocks is wellpreserved in the Hidaka Mountains, having a lot of information about the deep lithospherebeneath island arcs.

B-3-3. Origins of the Horoman Peridotite Complex and its Academic SignificanceThe peridotites on and around Mt. Apoi are scientifically well known around the world as the
Horoman peridotites, and are significant as a typical orogenic lherzolite. The Horoman peridotite
complex extends approximately 8 km from east to west and about 10 km from north to south, covering
the area along the ridgeline from Mt. Apoi to the north of Mt. Pinneshiri, and along the lower andmiddle streams of Horoman River, and the area near Mt. Horoman to the east (Niida, 2010).
The Horoman peridotites are characterized by a wide range of variety in peridotites types,
including dunite, harzburgite, spinel lherzolite and plagioclase lherzolite. Petrologically, they arecomparable to those in the composition range of upper mantle peridotites all over the world. These
diverse types of peridotite are interlayered with a remarkable number of thin layers of pyroxenite andgabbroic mafic rocks. The total thickness of the layered peridotite complex attains around 3,000
meters. As the Horoman peridotites are young and pure, the chemical compositions and the textural
patterns of minerals formed under the high-temperature and high-pressure conditions of the upper
mantle are also well preserved. It is well known that the Horoman peridotite complex is one of themost studied peridotite masses in the world (Appendix 1: List of Horoman Peridotite Publications).
The aims of research on peridotite complexes cover a wide range, and relate to the foundations ofearth science. They include elucidating processes of magma transport in the upper mantle, origins ofcompositional inhomogeneity of the upper mantle, mechanisms behind melt generation and melt
extraction, and solid-melt reactions during melt segregation to the Earth's surface. A further aim is toclarify the formation, modification, and evolution of the initial mantle in the earth’s history. The 4thInternational Orogenic Lherzolite Conference, held in Samani in 2002, was attended by around 100
scientists from 15 countries (Fig. B-18).

Fig. B-18 Memorial of the International Orogenic
Lherzolite Conference held in Samani in 2002.

- 19 -

Fig. B-19 Geological map of the Horomanperidotite complex (Niida, 1984) and major
observation sites.

Mt.Apoi Geopark,Japan

B-4 Listing and description of other sites of natural, cultural and intangible
heritage interest and how they are related to the geological sites and how they
are integrated into the proposed Geopark
As described in B-2, Mt. Apoi Geopark has five areas, each with its own geological andgeomorphological characteristics, and its own natural and cultural heritage elements. The geopark is
associated with a natural environment and local lifestyles closely related to the area’s peridotite andother geological / geomorphological characteristics. In this section, B-4-1 highlights non-geologicalelements by area, and the parts from B-4-2 to B-4-4 detail noteworthy natural and cultural heritage
resources.
B-4-1.

Summary of geosites with non-geological elements(1) Horomankyo Area
The entire gorge is covered in primeval forest, making the landscape even more spectacular. Amongother features, the area of Kitagoyo (P. parviflora var. pentaphylla) trees growing at the northern limitof their habitat across the side of Mt. Horoman is designated as a Natural Monument of Japan (Fig.
B-20). The Kitagoyo trees also form a unique plant community developed under the strong influenceof peridotites. Despite its low altitude, the area near a peridotite research site here provides a habitat toultrabasic plants found in the alpine area on Mt. Apoi. Hydroelectric power facilities (Fig. B-21) built
to leverage the gorge’s landform highlight the relationship between local industry and topography.

Fig. B-20 Japanese white pine habitat in Horoman (designated as a
Natural Monument of Japan; Geosite A3)

Fig. B-21 Horoman RiverPower Station No. 3 – astructure built to leverage
the gorge’s landform(2) Mt.Apoi Area
This area is characterized by internationally recognized alpine plant communities, which developed
under the influence of local ultrabasic peridotite. The flowers along the mountain trail here fascinate
climbers with their beauty. Diverse vegetation along with a variety of ultrabasic plant communities isfound in the area where peridotites are visible on the ground from near Rest Spot No. 4 to themountaintop. The steep terrain makes the land feel higher than it actually is, and the upper part of Mt.
Apoi affords sweeping views of the Pacific Ocean and the Hidaka Mountains (Fig. B-22). However,accelerated environmental change and anthropogenic factors caused the recent rapid decline of plantcommunities, prompting local residents and others to engage in plant protection and regeneration
activities (Fig. B-23). In this area, visitors can learn about the importance of the natural environment
and the link between the unique geological conditions and ecosystems.
(1)

(2)

Fig. B-22 (1) View from the Geosite B4 area; (2) Evidence of theinfluence of peridotites on Mt. Apoi’s alpine plant community- 20 -

Fig. B-23 Alpine plant regeneration
initiative involving locals, researchers
and the government (Geosite B2)

Mt.Apoi Geopark,Japan(3) Samani Coast Area
Intrusive-rock monoliths along the coast to the west of Mt. Apoi create a beautiful contrast with themountain. This unique landscape is the source of numerous legends passed down by indigenous Ainu
people, who have lived in harmony with nature here for hundreds of years. This area encompassing therocky monoliths and Mt. Apoi became a major transit point for thriving maritime trade with Japan’s
main island of Honshu in the latter half of the 18th century, laying the foundations for its development
today. In this area, visitors can learn about local history and lifestyles associated with the landform(Fig. B-24).
(1)

(2)

(3)

Fig. B-24 (1) One of the 33 stone statues of Kannon (the Buddhist deity of mercy), from which the name Mt.
Kannon derives (Geosite C4); (2) Tojuin Temple – one of three temples established in Hokkaido by the Edo
shogunate, and a structure that has witnessed the history of Hokkaido’s development (Geosite C5); and (3) arestored traditional Ainu cise dwelling (Geosite C8)(4) Hidaka Yabakei Area
Precipitous cliffs extend 6 km along the coast of the Pacific Ocean, into which the foot of Mt. Apoi
plunges. This area is believed to be where the Eurasian Plate and the North American Plate once
collided. It was also notoriously difficult to pass, dividing Hokkaido into eastern and western parts.
The cliffs are home to the Samani Mountain Path, which was built around 200 years ago (Fig. B-25).
At the bottom of the cliffs, high-quality Hidaka Kombu kelp (also known as Mitsuishi Kombu or
Laminaria angustata Kjellman) grows on nutrients from the region’s peridotite, and kelp drying
grounds covered with crushed peridotite are extensively found here (Fig. B-26). This area highlights
the history of locals who have overcome the issue of passing through the area and showcases theblessings brought by the landform.
(1)

(2)

Fig. B-25 (1) Samani Mountain Path (built around 200 years ago); (2) a
Wasuke Jizo statue at the Samani Mountain Path east trailhead (bothGeosite D6)

Fig. B-26 Hidaka Kombu
growing on nutrients from theregion’s peridotite

B-4-2. Unique ecosystems nurtured by the local geology(1) Alpine Flora on Mt. Apoi
Mt. Apoi provides habitats to nearly 900 species of vascularplants. The most distinctive feature of its flora is the sheer
variety of alpine plants present despite the mountain’s
altitude of only 810 meters. This is considered to stem fromgeological and climatic factors; the most salient of these is
the unique geology of Mt. Apoi and the surrounding area,
which is mainly composed of ultramafic rocks (peridotites).
Peridotites have a remarkably high content of magnesium
and nickel – elements known to inhibit plant growth. Fig. B-27 Sea fog engulfing Mt. Apoi in
Undeveloped soils in the region also tend to have low summer- 21 -

Mt.Apoi Geopark,Japanfertility due to their oligotrophic and dry nature. In addition, limited snowfall in winter tends to cause
freeze-thaw action within soil in windswept ridge areas. This action affects plants directly andindirectly by damaging roots and destabilizing soil on slopes. The sea fog that often engulfs Mt. Apoi
and the surrounding area also causes lower temperatures during the plant growth season (Fig. B-27).
These multiple factors inhibit forest formation in areas around ridges, thereby leaving more room for
alpine plant growth.
Mt. Apoi provides habitats to numerous endemic ultrabasic plants in areas around the ridge nearits peak, forming a unique floral environment. These include Hidakaso (Callianthemum miyabeanum),
Ezokozorina (Hypochoeris crepidioides) and Apoikuwagata (Veronica schmidtiana var. yezoalpina
form. exigua.). In particular, plants such as Hidakaso (a species from the genus Callianthemum, which
is localized in mid-latitude alpine environments in the Northern Hemisphere) and Ezokozorina (anendemic genus) are of academic significance. There are also four endemic species, one endemic
subspecies, eight endemic variant species, and eight quasi-endemic species among others. Such a
concentration of endemic species (including endemic subspecies, variant species, and others) is seen in
few places worldwide (Fig. B-28). This diversity highlights the role of Mt. Apoi and the surroundingarea as a stage for plant evolution. Relict species with markedly disjunct distribution, such as Kinrobai(Potentilla fruticosa var. rigida) and Ezorurimurasaki (Eritrichium nipponicum var. yezoense), also
grow in the region. The unique environment of Mt. Apoi is seen to have served as a refugium for theseplants, allowing them to survive today. Although the evolution of endemic species and the survival of
disjunct-distribution species are clearly attributable at least in part to the geological and climatic
factors detailed above, the geohistorical fact that the region has not been beneath the sea since the
Tertiary period (approx. 15 million years ago) is also considered important.
It should further be noted that the region is a hotspot for rare wildlife, with over 50 endangered
species living locally.

Fig. B-28

Plants endemic to Mt. Apoi

(2) Fauna on Mt. Apoi
Mt. Apoi and the surrounding area provide habitats to mammals, with brown bears at the top of thefood chain. These include Hokkaido sika deer, Japanese pikas, and Hokkaido sables (Martes zibellina
brachyura). Brown bears – Japan’s largest terrestrial mammal – require vast areas of land and diverse
environments for survival, ranging from seashores and waterfront areas to mountainous regions.
Although these animals are not sighted so often on Mt. Apoi or in the surrounding area, the highfrequency with which footprints, claw marks and other traces of activity are seen suggest that theregion’s favorable environment provides them with a supportive habitat. The close proximity of thesalmon-rich Horoman River and the alpine zone of Mt. Apoi with its abundance of dwarf stone pinecones – both of which are important for brown bears – create an environment found in few places inJapan.
Often referred to as relics of the Ice Age, Japanese pikas are generally seen as an alpine species inJapan. However, they are also found in areas at an altitude of only 50 meters or so in the HoromanRiver basin, which is known as their lowest-altitude habitat in Hokkaido (Fig. B-29). Pikas inhabit thecrevices between rocks on talus landforms, and geological conditions supporting the creation of such
- 22 -

Mt.Apoi Geopark,Japan

landforms are essential for their survival.
Hokkaido sika deer – Japan’s largest herbivorous animal – are also a typical mammal found on
Mt. Apoi and in the surrounding area. It is thought that they used to winter together in the region due
to its limited snowfall. However, the sika deer population has recently grown significantly, leading to
the disappearance of broad-leaved saplings and the decline of bamboo grass in woodland areas. There
are also concerns over their possible impacts on rare plant species in alpine zones (Fig. B-30).
(1)Fig. B-29 Japanese pika

(2)

Fig. B-30 (1) Traces of bamboo grass grazed by Hokkaido sika
deer; (2) installation of deer fences to support investigation of sika
deer’s impacts on alpine plants

Around 150 bird species are known to inhabit the region, andraptors such as falcons, buzzards and mountain hawk-eagles are often
sighted. As falcons nest on precipitous terrain, the coastal cliffs near Mt.
Apoi and in the surrounding area serve as prime nesting places. In
winter, Steller’s sea eagles and white-tailed eagles – both designated as
Natural Monuments of Japan – fly from the Eurasian continent to thecoastal area of Japan. Black woodpeckers – also a Natural Monumentof Japan – are often seen in forests at the foot of the mountain. In theridge area, spotted nutcrackers are frequently observed feeding on
dwarf stone pine cones and Kitagoyo (P. parviflora var. pentaphylla)
trees.
A small snail species named Apoimaimai (Paraegista apoiensis)
inhabits Mt. Apoi and the surrounding area. It is endemic to themountain and is found in cracks between peridotites (Fig. B-31). Its
brown shell, which measures around a centimeter in diameter, has hardhairs on its surface. It is suggested that the region’s unique geologicalenvironment, as represented by its peridotites, facilitated this speciation.
A
rare
disjunct-distributionsnail
speciesknown
asKadobarihimemaimai (Ainohelix editha var.) also inhabits Mt. Apoi
and its surroundings (Fig. B-32).
A notable insect species is the Himechamadaraseseri (Pyrgus
malvae) butterfly from the Hesperiidae family. It is found extensively
in northern parts of the Eurasian Continent, but its only habitat in Japanis Mt. Apoi and the surrounding area (Fig. B-33). The larval food plantof this species is almost exclusively Kinrobai (Potentilla fruticosa var.
rigida) – a rare species from the Rosaceae family. The region is also
home to Apoikiashioobuyu (Prosimulium apoina n. sp.) – an insect
described as a new species.

Fig. B-31
Apoimaimai(Paraegista apoiensis)

Fig. B-32
Kadobarihimemaimai (Ainohelix editha
var.)Fig. B-33
Himechamadaraseseri(Pyrgus malvae)(3) Bounties of the Sea off Mt. Apoi
The coastal waters off the Hidaka region, where Mt. Apoi Geopark is located, contain seaweed beds
providing habitats for kombu kelp and other forms of marine life. The kombu beds play a very
important role in conserving biodiversity and enhancing fishery output by serving as places of primary
production in this cold-sea area and acting as an environment for a variety of fish and shellfish.

- 23 -

Mt.Apoi Geopark,Japan

The kombu kelp species found along the coastof Mt. Apoi Geopark are Chigaiso (Alaria
crassifolia Kjellman), Aname (Agarum clathratum
Dumortier), Sujime (Costaria costata (C. Agardh)
Saunders) and Mitsuishi (Laminaria angustata
Kjellman). Local growth of Ma Kombu (Laminaria
japonica Areschoug) has also been observed. Amongthese, Mitsuishi Kombu, also known as Hidaka
Kombu, is the main type of seaweed found in thesebeds and is an important resource, accounting for
approximately 30 percent by value of the region’s
overall marine production. The species is not foundFig. B-34 Distribution of local kombu kelp
outside Japan, and thrives mainly along the Pacific
Coast of Hokkaido around Mt. Apoi Geopark (Fig. B-34).
It generally grows with Chigaiso and Sujime kelp on
rocks in relatively shallow waters from the intertidal zone
to depths of 8 meters or so. In the coastal waters off Mt.
Apoi Geopark, masses of long Mitsuishi Kombu kelp
grow densely at depths of 3 meters and less. Its
appearance when exposed at low tide is a magnificent
sight (Fig. B-35). At the eastern end of its distributional
range, the species is replaced by Naga Kombu (Laminaria
longissima Miyabe). The results of recent molecularphylogenic studies have suggested that Mitsuishi Kombu Fig. B-35 An exposed Mitsuishi Kombu
evolved from Naga Kombu and underwent speciation into community at low tide
Ma Kombu along the Pacific Coast of western Hokkaido. It has a close phylogenetic relationship withNaga Kombu, and genetic analysis shows that the two species form a phyletic group among Japanese
kombu types. No other species in the world are included in this group.
Mitsuishi Kombu was first noted in a publication by Swedish botanist F. R. Kjellman based on
his research on dried kelp for export to China. He had obtained the kelp from an English trading
merchant in Hakodate during a visit to Japan on a scientific expedition ship in 1879. The kelp products
he purchased are thought to have been Urakawa Kombu (“Uragaiva
Combu”), Samani Kombu (“Shamani Combu”) and Tokachi Kombu(“Tokatsu Combu”), suggesting that the species has been produced in
the area from the Hidaka region to the eastern Tokachi region sincethen, and that the coastal area of Samani has long been a production
area for this kelp variety.

B-4-3. Local History and Culture Relating to the Region’s
Geological Features(1) Ainu Hardships and their Restoration as an Indigenous
People
The culture of the indigenous Ainu people of Hokkaido is considered
to have originated with the marine-centered Okhotsk culture(400-800CE) and Satsumon culture (600-1100CE), which wasstrongly influenced by the culture of Honshu (Japan’s main island).
While the Ainu subsisted on hunting, fishing, and gathering, they
were also traders who traveled across the Tsugaru Strait to Honshu
and across the Soya (La Perouse) Strait to Sakhalin and the Eurasiancontinent. Hokkaido was a crossroads of civilization where Japanese- 24 -

Fig. B-36
Kelp (Kombu) Harvesting(Byozan Hirasawa, 1822–1876)

Mt.Apoi Geopark,Japan

culture met with the culture of the continent (Northeast Asia). The goods Ainu people sold included
pelts from land and sea animals (e.g., sea otters, seals, and sables), eagle and hawk tail feathers,
salmon, and kombu kelp. From the Middle Ages onward in particular, kelp was a main trade item inthe Hidaka region (Fig. B-36).
However, the increasing number of wajin (people of ethnic Japanese descent) from Honshu who
settled in Hokkaido in subsequent years gradually wrested the initiative of free trade from the Ainu.
When a trading system favoring wajin was established in the 18th century, Ainu people, who had been
producers and trading partners with the wajin, were forced to work and suffered great hardships
including discrimination and forced assimilation by the wajin.
In the 20th century, efforts to restore the Ainu as an indigenous people gained momentum. They
were encouraged to engage in activities that would preserve their unique language and traditionalrituals as well as other aspects of their culture. In Mt. Apoi Geopark as well, initiatives to promote theindigenous culture have remained ongoing, including the preservation of traditional dance and therestoration of cise (traditional Ainu dwellings) (see pp. 5 and 21).
(2) The Dawn of Samani Supported by Early-Modern Distribution Routes
In the 18th century, Japan witnessed full-scale development of its commodity economy anddistribution. With Osaka, often called the “Kitchen of the Nation,” and northern Japan connected byroutes across the Sea of Japan, large volumes of goods were traded (Fig. B-37). The routes extended to
the Kuril Islands just to the east of Hokkaido. Against this background, the region drew attention as animportant trading hub connecting the Kuril Islands and Japan’s main island of Honshu because Mt.
Apoi was a landmark when viewed from the sea, and more importantly, Cape Enrumu (a land-tiedisland composed of intrusive rock) served as a natural port (Fig. B-38).
In 1799, the Edo Shogunate that ruled Japan took the southern half of Hokkaido under its directcontrol in response to a sense of urgency over Russia’s ongoing southward expansion along the Kuril
Islands via the Kamchatka Peninsula. The shogunate established a kaisho (outpost office) at the baseof Cape Enrumu and built Tojuin Temple as part of efforts to win the hearts and minds of locals. To
facilitate the dispatch of troops for Hokkaido’s defense, the shogunate also constructed Hokkaido’s
first government-administered road, known as the Samani Mountain Path, on the sea cliffs (Hidaka
Yabakei) to the south of Mt. Apoi.
These developments are discussed as important themes in local history, and documents describing
them along with related structures and ancient structural remains have been designated as culturalproperties in recognition of their value in terms of local historical heritage.

Fig. B-37 A kitamaebune
merchant vessel and Meiji
Period (1868 – 1912)
marine routes

Fig. B-38 Cape Enrumu and Mt. Apoi, painted
around 150 years ago (“Hokkaido Rekiken-zu,”
Samani)(3) Kombu Kelp Harvesting – an aspect of local culture for the past 400 years
Commercial harvesting of local Mitsuishi Kombu is considered to have begun between the mid-17th
century and the 18th century. Much of the kombu kelp harvested in those days was transported to
Osaka in western Japan for the manufacture of kizami-kombu (dried shredded kelp), which laid the- 25 -

Mt.Apoi Geopark,Japanfoundations for the city’s development as a kelp
processing center. As this kelp species contains highlevels of iodine, it was also exported to China whereiodine deficiency was a serious problem, and wasused for goiter treatment (Fig. B-39). Its soft fiber
also makes it suitable for simmered dishes, and it
creates a mild flavor when used to make soup stock.
Due to a variety of uses not shared by other species,
Hidaka Kombu – the commercial name for Mitsuishi
Kombu – is widely known in Japan and is anindispensable part of the national diet. It is versatileand popular with the general public, but theFig. B-39 Kombu Road
differences in the areas along the Hidaka coast
where the kelp is harvest, known as shore disparity,
leads to variations in its commercial value. Different shores are ranked as extra- high quality, highquality, medium and regular, and prices depend on where kelp is harvested. Today, extra-highand high-quality shores are found in Samani, where Mt. Apoi Geopark is located, and intowns adjacent to it on both sides. However, Samani is the only town where all fisherydistricts are ranked as high-quality or above (Fig. B-40). This rich resource supports thediet of the Japanese both qualitatively and quantitatively.
Throughout the long history of Hidaka, Kombu harvesting and production areas have often faceddifficulties. These have included devastation of fishing grounds by oil pollution, environmental
degradation of fish habitats due to deforestation, and the decline of trade with China. However, thesecrises were overcome by the untiring efforts of local fishermen and related parties. Such work has
involved fishing ground improvement, product enhancement resulting in the production of sand-freekelp, drying ground improvement, and market expansion campaigns. In this way, traditional local
industry has been preserved (Fig. B-41).

Fig. B-40 Differences in the commercial value of
Hidaka Kombu among different production areas

Fig. B-41 Kelp harvesting using hooks thathave remained unchanged for 400 years- 26 -