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of some 115 miles from south to north. The width of the area is about 30 miles. It has not yet been found west of the Langeberg or east of the Kaap Plateau. In all cases it is succeeded by the Ongeluk volcanic series within about 30 feet. In the Good Hope outlier there are less than 12 feet of thin, bedded, dark quartzitic rock between the two, and the same is the case at Monjana Mabedi and Punt. At Juanana the intervening beds may be 30 feet thick. Generally there is a tract of low ground between the nearest outcrops of the Griqua Town and Ongeluk series, and it is only where hills made of the latter series rise sharply from the underlying beds that the succession has been clearly seen. The glacial beds have been found to underlie the Ongeluk series over a very wide area, and in nearly every outlier of the latter, the only exception being the Paarde Vley syncline, which has not been re-examined since the existence of the glacial beds was discovered, and there can be little doubt that the succession is a conformable one.
The source whence the chert and other rocks forming boulders in the glacial beds came is still unknown. The frequence of chert nodules should prove to be of material help in settling the question, but at present such nodules have not been described from South African rocks. The only similar nodule known to me from any other rock was shown me by Mr. D. J. Haarhoff, M.L.A., in Kimberley in April, 1906, and he says it came from the “ blue-ground” of the Kimberley Mine. This nodule is so like those mentioned above that I am inclined to believe that they all came from the same formation. The mode of occurrence of the chert in the Campbell Rand beds is not like that indicated by the form of the chert nodules in the glacial beds. As to the age of the Griqua' Town beds, there is nothing new
All recent writers on the subject are agreed that these beds are older than the Cape System of the south, but there is a difference of opinion as to the probable lapse of time between them. If, with Passarge (1) and Hatch and Corstorphine (2), we regard the unconformably overlying Matsap beds as the equivalents of the Table Mountain series of Lower Devonian or Silurian age, the Griqua Town beds may not be very much older than those periods. We know that after the deposition of the Griqua Town beds there took place a great outpouring of volcanic rocks in Cape Colony, and that both the volcanic rocks and the underlying sedimentaries were subjected to earth movements and prolonged denudation before the Matsap beds were laid down. This correlation of the latter with the Table Mountain series is, however, of doubtful value. It is based chiefly on two facts ; first, a certain degree of lithological resemblance, and, second, the fact that both are older than the Dwyka series, and rest unconformably upon still older rocks.
As to the lithological resemblance, when we have stated that both groups are largely made of quartzites, with occasional thin bands of pebbles and isolated pebbles, we come to the end of the similarity.
(1) Die Kalahari, 1904.
(2) The Geology of South Africa, 1905.
In colour, in modes of weathering, and in general appearance, the two groups are not alike; the Matsap beds are, on the average, coarser in grain than the Table Mountain beds, and the purplemottled tints of the great bulk of the former are foreign to the latter ; the Matsap beds do not give rise to the peculiarly-curved, wind-worn masses of rock, with accumulations of iron oxides and silica in some parts and a loose, sandy texture in others which have been observed in the Table Mountain sandstone, from the Pondoland outcrops to the westernmost exposures in Calvinia. The surface of the Matsap areas is covered with large and small blocks of quartzite, with rounded corners; the rock breaks down into its component grains much less readily than the Table Mountain sandstone does; in the Langebergen of Griqualand West the ground on the top of the mountains is hard, sandy soil between the outcrops and boulders of quartzite, while in the Langebergen of the south coast and other mountains made of the Table Mountain series, the interstices between outcrops are filled with loose white or black sandy soil.
The chief objection to the correlation is to be found in a comparison of the structural features of the north and south of the Colony. In the south the earth-movements which produced the ranges made of the Table Mountain series took place long after the deposition of the Dwyka series, and there is a sequence of conformable rocks from the base of the Table Mountain series into the Karroo formation. In the north there is a great gap between the Matsap beds and the Dwyka. Near Piljaar's Poort there is an outlier of the normal northern type of Dwyka till lying between the forked ends of one of the Langeberg group of hills, and one of the chief constituents of the boulders is the Matsap quartzite; there is no doubt that the northern Langebergen were in very much the same condition during Dwyka times as they are in to-day. They have probably lost something in altitude by denudation, and new valleys have been cut in them, but they stood in the same relation to the older rocks east and west of them as they do now, and they do not appear to have suffered any further crumpling. Except that these earth-movements which affected the Matsap beds in the north took place in Pre-Dwyka times, we have no direct evidence of their date as compared with the southern rock-systems, but a further comparison of the geology of the two regions will throw more light on the question. The Matsap beds are certainly some thousands of feet thick ; four thousand feet can easily be accounted for in the Langebergen, near Pad Kloof, and the top is not known. These beds originally stretched over a considerable part of Hay and southern Bechuanaland, at least as far as the Paling-Gamagara and Matsap ridges, which are outliers of the formation ; a great part of this sheet of rock must have been removed in Pre-Dwyka times, for at Piljaar's Poort the outlier of Dwyka till mentioned above very probably rests upon the Griqua Town beds which crop out in the immediate neighbourhood, between the Dwyka and one of the Langeberg ridges. Now, if the Matsap beds are taken to be the equivalents of the Table Mountain series, the earth movements that crumpled the northern strata and the denudation which removed
such large masses of the northern rocks must have taken place during the Bokkeveld-Witteberg times, represented in the south by some 5000 feet of rock. This seems to me improbable, and the only way to avoid the difficulty is to regard the Matsap beds as older than the Cape system.
Assuming that this argument is good, the Griqua Town beds, which are overlaid unconformably by the Matsap beds, must be very much older than the Cape system, and though there is no direct evidence, they may quite well be of Pre-Cambrian age.
AND PEARS IN CAPE COLONY.
By J. B. Pole EVANS, B.A., B.Sc., PLANT PATHOLOGIST.
There are two distinct diseases affecting apples in the Colony. The one under discussion in this note affects the leaves, twigs, and fruits of both apple and pear.
The fruit, the most important article from the grower's point of view, is attacked at all stages of development, but especially after the petals have fallen and the fruit is no bigger than a marble.
To such an extent is the young fruit affected at this stage that it usually shrivels and drops off.
The appearance of the disease to the naked eye is the same in all cases; usually round, rough, dark, olive-green and velvety patches appear on the leaves, twigs and fruit.
The fruit, if it continues to grow in spite of these spots, nearly always does so at the expense of cracking.
Cutting such an apple across shows that internally it is quite healthy.
The other disease, a far more serious trouble, is known locally
Externally this disease is only seen on fruit which is nearing maturity, and, what is more serious still to the exporter, appears on apparently sound apples, after they have been packed in cold storage.
To the naked eye this disease appears first as smooth, darkgreen, and slightly sunken depressions usually towards the upper end of the apple. Later on these depressions turn brown, then black in colour, and entirely disfigure the whole apple, and, further, when the apple is sliced open it is spotted here and there with masses of dry brown tissue.
With regard to this latter disease we shall have nothing further to say here.
As far back as 1888, Professor MacOwen attributed the disease on certain leaves and fruits of the Saffraan Pear to the fungus Fusicladium dendriticum, Fckl. He also reported that he had occasionally noted the same fungus on Apples in the Colony.
As some doubt has recently arisen with regard to this disease, I was invited to visit Cape Colony during the month of March and investigate the matter.
Some of the results of this investigation are put forward in the present note, the object of which is to show that there are two specific fungi present in Cape Colony, namely Fusicladium dendriticum, Fckl, attacking Apples, and Fusicladium pirinum, Fckl., found on Pears.
The general appearance and occurrence of the disease in the Colony has been dealt with by Mr. Lounsbury in the Cape Agricultural Journal, No. 14, of 1905, so that without travelling over old ground we shall confine ourselves to the miscroscopic investigation.
For this investigation, a large supply of material, including diseased leaves, twigs and fruits of both Apple and Pear collected from various orchards in the Colony, was forwarded from time to time by Messrs. Lounsbury and Dewar, Government Entomologists at Cape Town and Grahamstown. In addition, while in the Colony in March, material of diseased Pear was obtained at Worcester, Paarl, Stellenbosch and Cape Town, and of diseased Apple at Stellenbosch.
All the material examined was found to be producing abundant conidia from the disease spots. From the nature of these conidia and their conidiophores, it was evident at once that we were dealing with two distinct fungi. In spite of this fact, a sharp look-out was kept to see if infected Apple material ever showed signs of being infected with the fungus found on the Pear, or Pear material to be attacked with the fungus found on the Apple. No indication of this was found in any of the examinations.
By some authorities the fungus occurring on the Apple is considered to be identical with that on the Pear ; by others they are regarded as two distinct species.
To constitute a specific difference between two plants, we must be able to point to some morphological character by which we can distinguish the one from the other. A reference to the figures of these two fungi will, I think, clear up any further doubt regarding them.
FUSICLADIUM DENDRITICUM, FCKL.
In Figure I., Plate, p. 268, is shown a section through a small disease spot of F. dendriticum on the Apple, of the variety known as the Late Bloomer." It will be seen that the mycelium bursts through the epidermis, and a succession of spores is constricted off in a continuous fashion.
The ripe conidia (Figure II. a.) when sown in water soon germinate (Figure II. b.). The spore always becomes septate, and gives rise to the germ tube (Figure II. b. and c.), which eventually bears secondary spores.
FUSICLADIUM PIRINUM, FCKL.
In Figure III., Plate, p. 268, is shown a section through a disease spot on the Pear, of the "Saffraan” variety. For some little time the myceliuni remains covered by the epidermis, through which it sends up here and there, stout conidiophores, which have a studded