In the present field several kinds of faults are recognized such as normal, thrust, r e - verse, rotational types. Among the many recognized faults several of the more important are named and only those which have direct relation with the geological structures are plotted in the geolgical map whereas the minor ones which are associated with major ones ox which do not have significance with the geological structure were omitted. Those given names will be described in the order mentioned above.
B-1. Kishinoshita Fault (PI 1, Fig. I )
This i s a normal fault stretching from Kishinoshita, Niihama City in Ehime Prefecture east-west with the northern side thrown down, eastwards for two kilometers. By this fault only the upper Pleistocene alluvial deposits are cut, and a distinct fan-scarp is preserved. This was first recognized by TSUJIMURA and TANJI (1932).. This fault i s considered to extend westwards from Kishinoshita to fan-scarp in the vicinity of Ishioka Shrine in the north of Komatsu City for about 12 kilometers.
B-2. Saragamine Fault
This is a normal fault extending along the northern slope of Saragamine in Onsen-gun, Ehime Prefecture for six kilometers in east-west direction The strike i s N 70' E with 70' S dip. This fault cuts the Ishizuchi group. The fault of nearly the same type as above mentioned is developed about one kilometer in its north
B-3 Toyooka Fault
This is a normal fault extending from Kobayashi, Doi-cho in Ehime Prefecture for about six kilo- meters to Nishisangawa, Toyooka-cho The general trends E-W with the norhexn side thrown down. By this fault only the upper Pleistocene fan deposits a r e cut, and a distinct fan scarp is preserved.
B-4. I,yo Fault
This is a normal fault assumed to extend from Konogawa, Kaminada-cho, Ehime Prefecture for about 10 kilometers to Ueno, Iyo City in the same Prefecture The general strike is ENE-WSW with northwestward throw. This fault occurs between the Izumi group and the Gunchu formation, and in the southwestern part, it exends into the Izumi group and is formed a crushed zone there
B-5. Tambara Fault
This is a normal fault assumed to strech from Nagano, Tambara-cho in Ehime Prefecture for about 10 kilometers to Kusunoki in the same township. The general strike is N 10" E with eastward throw.
This fault cuts the Izumi group and is cut by the Okamura fault which is a rotational fault B-6. Ryuozan Fault
This is a normal fault extending from Nishinokawayama, Saijo City, Ehime Prefecture north-northeast- wards for about 12 kilometers t o Tsugoshi in the same City where i t comes into contact with the Median Line. The strike is almost NNE-SSW dipping about 80 degrees to the west and extends through the Sambagawa metamorphics. This fault is covered by the Eocene Kuma group and is thought to have had relation with the folding of the Izumi group at the end of the Mesozic
B-7. Kawauchi Fault
This is a normal fault extending from Otoda, Kawauchi-cho, Onsen-gun, Ehime Prefecture to six kilometers southwestwards through the Izumi group. In the vicinity of Otoda, this fault is nearly
The Geolog,y
o,fKagawa and Northern Ehime Pre,ftctures
vertical and cuts the sanukitic andesite B-8. Kaburazaki Fault (Pl. 7 , Fig. 1)
This is a normal fault extending from Nagahama in Tonosho-cho in ShBdo-shima for about 1.5 kilo- meters to Oe in the same township The general strike is N 55" E with dips of 65' SE. This fault occurs between the Tonosho group and the Paleozoic rocks and between them there is developed a 10 meters thick crushed zone and a 30 centimeters thick fault breccia and gouge, the latter above the former. At the road side cliff in Oe, there are found a number of fissure filling-like deposits developed in the Paleozoic rocks along the fault I t could not be determined whether the Miocene conglomerates were dragged into the clayslate of older rocks due to faulting or whether the former were deposited in a small crevice of the latter assoiated with faulting. From this evidence i t is considered that there were two times of fault activity, once before deposition of the Miocene sedimentaries and again after deposition of the Tonosho group and before deposition of the Sanuki group. In other words the southeastern part of the thrown down side was eroded away before deposition of the Miocene Tonosho group, and faulting occurred along the unconformity after deposition of the Tonosho group, The same type fault a s above mentioned occurs between the Tonosho group and the Paleozoic rocks or granitic rocks with N-S trends or ENE-WSW trends, namely the Mime fault. (P1 1 , Fig. 2)
B-9 Monnyu Fault
This is a normal fault and is observed at Monnyu-ike, Okawa-cho, Kagawa Prefecture. This fault is conside~ed to be a large one because of having 20-30 centimeters thick fault clay or gouge, i t s strike is N 20" W with 40' NE dip. Although its extension can not be determined because of cutting the Ryoke g ~ a n i t e i t i s considered to be an important one
B-10. Gunchu Fault (P1 7 , Figs. 4-5)
This is a thrust fault extending from the reservoir in Mori about three kilometers southwest of Iyo City to 1 5 kilometers farther southwestwards By this fault the Izumi group rides over the Gunchu formation. The general trends N 60" E with dip of 20" SE in the southwestern part whereas in the northeastern part the dip angle is not clear
B-11. Okamura Fault (P1
8 ,
Fig. 7)This is a rotational fault extending or traced from Daito in Komatsu City, Ehime Prefecture east- northeastwards to Kamenoko in Niihama City for a distance of 17 kilometers. This was first recognized by NAGAI (1954), who claimed it to be a reverse fault.. This fault comes between the Izumi group and the Okamura formation This fault is considered to extend westwards from Daito to the Matsuyama Castle in Matsuyama City for about 25 kilometers through the Izumi group but near the Matsuyama Castle the fault separates the Izumi group from the Ryoke granite with strike of N 70" E and 40"
N
dip. This fault is considered to be a rotational fault because the dips change and the fault is both a normal and reverse one along the same line..
B-12. Shimone- Tsune,yama Fault
This is a thrust fault extending from Tsuneyama in Tomisato-mura, Uma-gun, Ehime Prefecture west-northwestwards for about 20 kilometers to Daishoin, Niihama City where i t comes into contact with the Median Line. The strike is almost east-west dipping about 45 degrees to the south and extends through the Sambagawa metamorphics. This was named by KOJIMA (1955).
This is thought to have had relation with the folding of the Sambagawa matamorphics a t the end of the Paleozoic.
B-13. Ebata Fault (Pl. 8 , Fig. 6)
This is a thrust faul textending from Kawauchi, Yamamoto-cho, Kagawa Prefecture to Eabta in Manno- cho for about 20 kilometers in N 60" E to east-west trend The dip is towards the south or southwest a t about 40--50 degrees. The Izumi group rides over the Kawauchi formation. Near Nakato in Kotonami- mura, Kagawa Prefecture, this fault extends into the Izumi group and because having the same strike and dip as the Izumi group its tracing is difficult but sometimes This is covered unconformably by the Yakeotoge gravels. This fault corresponds to the Kubo thrust of IMAMURA and NAKANO (1950).
The thrust fault having the same strike and dip a s above mentioned fault extend into the Izumi group in its south and makes the crushed zone.
B-14. Kikaku Fault (Pl. 8 , Fig. 8 ; PI. 9, Fig.
8)
This is a thrust fault and is observed a t the road side cliff in the south of Kikaku-Park, Nagao- cho, Kagawa prefecture.
By this fault the Ryoke granite rides over the Taman formation and the higher terrace gravel and between them there is developed a one meter thick white fault clay and the Ryoke was crushed and
44 M. Saito
disturbed for a fairly long distance in width. The strike is almost E-W dipping about 20-30 degrees to the south and although of considerable magnitude, this fault can not be traced for any great distance because of being covered by the lower terrace gravels or alluvial deposits.
Also similar thrust is observed at the south cliff of Kabutoyama in the west of Zentsuji-City.
There the Ryoke rides over the tuff breccia of the Oda formation.
B-15. Setoucki Faults
From the directions of the bays, crevices and inlets of the islands studied in the Setouchi Sea, the peninsulas and the many blocks (namely, Yashima scarp) observed on the mainland, the orientations of the islands themselves, the relationships of them to the structures observed on the mainland, and faults observed on some of the islands, it is thought that there are two different trends in the fault system of the Setouchi area. One system trends roughly in east-west direction (ENE-WSW) parallel with the shape of the present Setouchi Sea and the other is transverse to it or roughly north to south in direction (NNW or NNE) These different fault systems are thought to have had bearing on the development of basin of the Setouchi Sea and to have had control or at least great influence on the trends of the longer axis of the respective islands and of the directions of the inlets, coves, embayments and other features now preserved there.
C Median Line
The Median Line a t different localities shows certain features of interest a s described below according to locality.
At Inuyose -toge (pass), Nakayama -cho, Iyo-gun, Ehime Prefecture, the strike of the Median Line is N 40' E with 40' N dip, and the sandstone of the upper part of the Izumi group in the form of pseudoconglomerate rides over the green schist of the Sambagawa metamorphics. At Oiwabashi, Tobe- cho in the same township, the Izumi group rides over the Kuma group with fault strike of N 45" E and 45" N dip. Here the Izumi group is considerably disturbed for a thickness of about seven meters where there is developed tectonic conglomerate cemented with black mud. At Inai in Kawauchi-cho, Onsen-gun, the Izumi group and Kuma group are in contact but the contact could not be observed However, the strike and dip of the Kuma group is N 80" W , 30" S whereas that of the Izumi is N 75"
W, 50" N, and the relation is considered to be a thrust, with the latter riding over the former.
At Yuyaguchi, Tambara-cho, Onsen-gun, Izumi group rides over the black schist and the fault plane strikes almost east-west and the dip is about 20 degrees towards the north There is developed a one meter thick mixed breccia zone of sandstone and schist, and four or five meters thick felsitic rock having sandstone fragment as xenolith like and the black slate of the Izumi group in contact with the Sambagawa metamorphics is disturbed over a considerable distance Here the strike of the Izumi group is N 70" E with 50' S dip, whereas that of the Sambagawa is N 40" W with 40' N dip. (PI 8, Figs.
1-3; P1.
7,
Fig. 2)At Banya the vicinity of Ichinokawa, in the south of Saijo City, Ehime Prefecture, a fault plane striking N 70' E with 40' N dip separates the Izumi group and the graphite schist of the Sambagawa metamorphics This is probably a thrust fault.
In the valley in the east of Kawaguchi, Nakahagi in Niihama City, the black schist and felsite with east-west trend and dip of 30 degrees towards the north and 10 centimeters thick fault clay is in contact with the Okamura formation This is probably a normal fault (P1
8,
Fig 5)In the valley bottom a t Mikura in Niihama City, a one meter thick black colored fault clay lying over the schist of the Sambagawa metamorphics can be observed but because of being covered with the gravels of the present streams it could not be determined what formation is in contact with it
In the valley in the south of Kinogawa, Doi-cho in Ehime Prefecture, the Sambagawa metamorphics and Izumi group are in contact with a fault Although neither fault nor fault clay could be observed, it is thought that a fault occurs because the Izumi group strikes east-west with N 40" dip whereas about 20-30 meters therefrom the dip becomes 30" S The strike of the schist near the assumed fault is N 40" E with 50" N dip Although the fault is assumed the kind remains unknown.
At Urayamatani, Doi-cho, Ehime Prefecture, the Izumi group is in contact with the Sambagawa schists, and the fault plane is N 70" E with 30' N dip For a thickness of about 30-40 meters from the fault plane the Izumi group is disturbed and forms a crushed zone and a t the place nearest to this zone the Izumi strikes east -west with 4S0 N dip, whereas the black schist of the Sambagawa metamor
-
phics the strike is N 70" E with 65' N dip At the road side cliff about 500 meters south of Tsubakido