ARTICLE III. RESEARCHES INTO THE GEOLOGY OF FORMOSA.* BY GEORGE KLEINWÄCHTER, Esq. Na journey from the South Cape to Takow and on different other excursions which I undertook during my stay in Taiwan, I had occasion to make some observations on the mineralogical composition and geological formation of Formosa. I am aware that they are imperfect and only comprise some parts of that island, a fact which might deter me from giving these notes publicity, were it not, that even a few established facts may be of interest and further the object of true Geology, which is to arrive at a complete knowledge of the constitution and history of every part of our globe. Formosa must still be considered as a "terra incognita." We know that large mountains nearly bisect the island, that the plain on the west is inhabited by the Chinese and the East by Aborigines, socalled Savages. We know what her soil produces, but we know not, what her soil consists of and what treasures are hidden under it except in the northern parts, where now Coal mines and Petroleumn wells are worked. Names have been given to the most prominent peaks and their heights have been ascertained or estimated; but beyond that nothing is known of the outlines of these mountain ranges or the valleys between them; and of the physical aspects of the East coast we are still less able to judge, it being closed to our view. This is however not astonishing. Those whom their vocation leads to this island, have other pursuits to attend to and those, who did spend a few days in the interior, went there out of curiosity or for Ethnological studies. The *Read before the Society on the 17th April, 1883. attraction of the Savages naturally led to a neglect of the country they live in, hence few observations of a geographical and none whatever of a geological nature have ever been made or brought to notice, at least as far as the South and centre of Formosa are concerned. Want of time has also prevented me from making long travels of exploration and obliged me to confine myself to South Formosa only, i.e. to that part of the Island which lies between the 22nd and 23rd degrees of latitude. The following are the results of my investigations: The southernmost end of Formosa on an average 5 miles broad, is protected against the waters of the ocean by two hill ranges, which run along the east and west coast; the one, called the Gooswa Promontory extends from the South West Cape in a straight line 7 miles northwards, its two highest points in the middle and towards the end being 538 feet and 627 feet high, respectively. The other range commences with the South Cape, runs gradually rising towards northwest, opens into a broad plateau and turning to N.E. terminates at the Savage village Shamalee. Four miles to the north west of the South Cape is a peculiarly rugged hill, 1,035 feet high, from which the land slopes gradually towards the east range forming another plateau. From Shamalee westward extends a double peaked ridge, and south of this the land is further divided by two parallel ranges, rising to more than 2,000 feet, one of which terminates in a cone shaped mountain,-Remarkable Peak,-1,083 feet above the level of the sea. of the Gooswa Promontory and Bay hill, which is a small isolated hill, south of Expedition Bay, lies a level tract of land, at its widest part 3 li broad. In the middle of this, at the foot of the Shamalee range is the District Capital Hêngch'un-hsien, and in its northwest corner at the mouth of a broad river lies Chê-chêng sive Langchiao. A mountain vis à vis to this walled village and bearing the same name forms the link between the hills south and north, divided from the one by a deep chasm and from the other by the Langchiao river. East Turning now to the composition of all these capes, moun tain and hill ranges, we find in the cliffs at South Cape abundant remains of corals, which make up almost the entire mass. The crest of the east range is a series of limestone rocks with fractures and fissures, and the west range shows the same towards the seaside, but its top and inland slopes, as well as the surface of South Cape and the eastern slope of that range are covered with calcareous sand. The beach round Kualiang Bay consists of fine coral sand, and numerous recent Zoophytes red and white are found. The other mountains are thickly wooded in luxuriant tropical vegetation, the trees and shrubs which cover them up to the summits, have protected their surface from the wasting influence of atmospheric agencies, their underlying formation therefore is not so apparent to cursory observations. At one spot, however, the waters of an extensive spring have laid it open and disclosed strata of limestone. This spring, by the way, is situated in the territory of the Kualuts in a beautiful forest. Women and children of the savage tribe were sitting around it and filling their bamboo tubes with water, when I approched on the way to their village. As my escort informed me, this spring has high qualities in curing wounds and smallpox. It belongs probably to the class "Earthy waters" of which the chief contents are sulphate and carbonate of lime. The cone of Remarkable Peak is of compact limestone, limestone rocks reach out of the water at several places along the shore of Kualiang Bay, and within the walls of Heng-ch'un-hsien I again found a large pile of Limestone Rocks. The soil which forms the upper layers in this district is throughout of argillocalcareous nature, varying from soft earthy shale at the foot of Remarkable Peak to fine yellow clay exposed by the rivulets of the plain. On the mountains between Langchiao and the Pacific Coast "bright flames" have often been seen "jutting out of the hardbaked earth," a statement which, as I have not been there myself, must at present suffice for our researches into the composition of that region, though all details as to the height at which this phenomenon was seen and as to the nature of she ground are wanting. The hardbaked earth probably was thale or mudstone, similar to that, which I found on Sugar loaf hill (see further on). The flame may be caused by the ignition of sulphuretted hydrogen, which would point to volcanic action, or by the ignition of the vapours of a petroleum spring, which would point to underlying strata of coal or bituminous shale and sandstone cavities. On the whole I think the latter explanation more probable. Coal indeed has been shown to me by the District Magistrate as having been found within the limits of his jurisdiction. The Langchiao river finally gives evidence of Sandstone by the reddish fragments which it contains. Let us now follow the military road, which connects this southernmost part of Formosa with the great plain. Immediately after leaving Langchiao it passes over the east side of a low hill, apparently a sanddune, which forms Langchiao point, goes along the bay of the same name on a strand of coral sand and ascends the slopes of a sugar loaf shaped hill, 411 feet high, which fall steep to the sea and consist of mudstone containing iron. From here stretches the Liliang ridge 6 miles northward, the two southern summits of which rise to the heights of 2,263 and 2,437 feet, and the northern one, near the town of Hongkong, to 3,365 feet.* The gentle slopes of this range form a "raised beach," below which a second one has formed, covered with large sandstone pebbles, débris of the formerly surfworn upperterrace. Some of these are red, others variegated, showing yellow, bluish, reddish and purple lines, some show streaks of quartz, all of them sparks of mica. Corals and coralsand do not reach beyond Langchiao Bay. At one spot, among others, where a spur reaches the sea, the road was cut through the solid rocks and disclosed dark red breccia. Horizontal lines and Tideripples were visible at different places on the sandstone cliffs at a height of about 50 feet. Further on the strip of land, which runs between the sea and the mountain range, gradually widens into a sandy tract, on which a few acres have been cultivated with rice and sugar. The cliffs are overgrown with brushwood; but where torrents break over them, white sandstone rocks (quartzites) *These figures are taken from the "China Sea Directory." are uncovered, and a section showing huge boulders of the same material covered by gravel and sand was also laid open to the eye. The town of Hongkong is beautifully situated, 30 li from Langchiao, on an alluvial tract of dark sand covering strata of flagstones, which extend to the sea and form a bar round the shallow harbour. They are deposits from the two mountains, which here meet the Li-liang Sua. The coast line northwards. shows shingle of a similar nature; houses and walls are built of these dark-grey sandstones; they are less micaceous than the before mentioned red ones but are mostly traversed by veins. of quartz; of the specimens collected one shows crystalization, the other both this and slaty texture. 5 li north of Hongkong another mountain torrent enters the sea, its banks are precipitous and at its mouth a dark cliff rises, which from its shape is called "Saitou," i.e. Lion's head. 2 miles further on, on similar ground as Hongkong, also pierced by a small river and surrounded by a stonebar, lies the village of Chetonka. The same may be said of Namchieh, the next station on the road. Except at these points the coast is bold and steep, the hills in some places descending almost to the waters edge. On one of these projections, where a fort has been built on the rocks, I met with traces of coralline limestone; otherwise this part of the coast consists of white sandstone cliffs like those before Hongkong. From Namchieh I made an ingress among the mountains. After crossing the alluvial plain, I arrived at a gorge through which a river flows; from its entrance a level terrace extends towards the seashore, and at the other side a narrow valley opens to the left and right, partly cultivated. I followed the river eastward and ascended one of the hills, where I had opportunity to observe the physical aspects of the neighbouring mountains: this district is made up of detached rounded hills and short anticlinal ridges, whilst parallel ranges striking from North to South are the general character of the southern system. The scenery here is also wilder and more picturesque. The specimens collected near Namchieh belong to the Clayslate group, of various description and different gradation of metamorphosis. |