406 THE COLLIERY GUARDIAN. March 3, 1916. are the Soederlian (Upper Pliocene), Diestian (Lower Pliocene), Bolderian (Miocene), Rupelian (Middle Oligocene), Tongrian (Lower Oligocene), Ypiresian, Landenian .and Heersian (Lower Eocene). In the west of the Campine the Aschian is the most prominent member of the Upper Eocene; and the Middle Eocene (Laekenian and Brusselian) is confined to this district. The Heersian and Landenian sands, both of which extend over a large area, contain water under pressure. The former obtain their greatest thickness (150 metres) about the longitudinal axis of the field, but whether this is also the case with the Heersian has not yet been ascer- tained. However, the lines of total thickness of the tertiary formalion have been determined and found to run west-north-west. The lines indicating differences of 100 metres, from 100 to 600 metres, are fairly parallel and clearly show the considerable increase in thickness toward the north-north-east. Near the Meuse the Hires are less regular and indicate the existence of an important series of faults extending to the north-east. Chalk.—Only the upper divisions, Maastrichtian and Senonian, are found, the former having a maximum thickness of about 70 metres, whilst the latter is sub- divided into the Spiennes beds (50 to 60 metres), Nouvelles beds (30 to 224 metres), and Herve beds (maximum, 159 metres). The behaviour of the lower edge of the chalk is a matter of special interest for future mining operations in the Campine. The lines of equal height of this lower edge run in a general west-north-west direction, fairly parallel with the lines of the tertiary, with the same indications of disturbance near the Meuse; but ;he thick- ness appears to increase more rapidly in the south-east of the district than in the north. Permo-Trias and Red Carboniferous.—The red strata entered in the borehole tables as permo-trias have not yet been fully identified. The author’s experience in the Munster basin has shown that the red coloration of carboniferous strata never reaches to any great depth, and mostly a few yards only, so that a further examina- tion of these Campine strata is desirable in order to ensure proper classification. In the one borehole (No. 64) the red permo-carboniferous strata occupy a total thickness of 647-65 m. in three divisions, the upper- most being rich in gypseous, calcareous, and marly beds, whilst the middle one is largely sandstone, and the lowermost is characterised by blue schists. Strata Underlying the Coal Measures. Carboniferous Limestone.—The number of borings in the Campine which have penetrated the palaeozoic strata under the carboniferous is small. In No. 38 bore, at Kessel, however, the whole of the stages (Visean, Dinantian, and Tournaisian) of the carboniferous lime- stone have been traversed. This formation extends as a continuous belt along the southern boundary of the pro- ductive coal measures of the Campine. Devonian.—This includes the Famenne and Frasne stages (Upper Devonian), corresponding to the Clyme- nian and Intumescens stages. Siluro-Cambrian.—Borehole No. 44 encountered grey schists, of Silurian or Cambrian origin, at 191-60 to 219-90 m., and these strata have been detected in the plateau of Brabant, southwards of the Campine. Water-Bearing Cover Rock and Shaft Sinking. An important point in connection-with the sinking of shafts is the thickness of the cover rock. In 1903, J. Kersten calculated the mean depth of the upper edge of the carboniferous in the province of Limburg as 533 m., in the province of Antwerp as 666 m., and in the Campine, as a whole, 554 m.; but the author’s esti- mate, based on later provings, as about 600 m. in the east and 700 m. in the western portion of that district. The second important factor in the same connection is the petrographic character of the cover rock. Generally speaking, a remarkable petrographic change occurs in the Tertiary from east to west. In the east (Belgian Limburg) there are great thicknesses of sand, increasing in the northward direction, and bearing large quantities of water. Under them is the upper chalk, consisting mainly of limestone and marl, with the Aachen sands as the lowest member. In the west (province of Antwerp) the tertiary sands decrease in favour of the thick zone of the Rnpelian and Tongrain, the upper chalk here consisting of hard Senonian marls, with flints, and with green, sandy Hervian strata as the bottom member. The sands in the western district seem to contain less water than those further east, some of the borings being dry; but it would be hazardous to rely on this, since water under a pres- sure of 30 to 50 atmospheres was met with in borings on the southern boundary. It is important to put down boreholes before sinking shafts, since, where this has been done, valuable infor- mation has been obtained on the petrographic character and wetness of the cover rock. In trial borings, on the other hand, these points have been less considered than that, of getting down to the coal measures as quickly as possible. With the system adopted in the Campine of making the preliminary borings with a double core tube, it is also possible to obtain cores from soft strata, and these cores are more valuable to the geologist than the material brought up in water-flush boring. The various ground water horizons are summarised below :— At Comparatively Moderate Depth.—In the Diluvium occur : Hesbayian (water-bearing) and Mosean (with two horizons, the lower containing extensive feeders). In the Pliocene to Miocene : Poederlian to Bolderian (two powerful springs in glauconitic sand, and a more impor- tant water horizon at the base). In the Oligocene : E CQ in no 0 in £ 9 _ go /oo aoo 10 -----(♦8O> 566.56 E Explanation 14 Borehole Number t^^) UFl BBT of BOREHOLE ABOVE SEA-LEVEL 2-83 TOR OF COAL MEASURES 522.83 65 ---- $43.19 817.97 ------ DATUM LEVELS BOTTOM OF COAL MEASURES 30 Sdsoo^P '660./^ , 19 7843c —13- (♦81) 14 (♦82) 522.33 8 56.1-8 50 (♦37) • 387.30 9 46 20 (+39) 8 (♦78) 412," •60 5 (♦66) 1 - 4H$.to +85.SO 24 (★9/) 460.60 'g/S.OO 5Z8./3 535 50 626.30 370.00 558.00 4+3.00 47 (*f) 23 -- 55 (*52.50) - - , 62 ex (★4/so) 54 65/.50\ 5&€|L50 CD 3 tn ro O cn 56 2 So) .70 533 927.00 789.40 55/.40 IS (♦62) 8/7.97 404.00 764.00 994,42 743.80 785.30 536.00 II -----W 400.00 21 (♦45) 405.00 538.68 560.4-0 1000 /34.00 670.15' 8/206 ------12- (★75) 36/00 5(72// 702.00 ___ (★SOL 505.30 -28—r (★28) 528.50 29 (♦32) 573P0 ^|7 62ff50 494./0 481.00 61 (>93) /6 (♦40) 22 26 (♦32) (*354 47500 (★51) 420.50 32 (★45) 368.00 131 .00 3/7.00 6/5.05 7/9.78 724.44 970,00 677.25 Fig. 5. Rhine lignites (water under pressure in many places); Rupelian (springs in sands separating the clays); Tongrain (artesian water at the surface with a pressure of 14 atmospheres). In the Eocene : Brusselian (springs in the sandstone). At the Junction of Tertiary and Cretaceous.—Strong influxes of water in all borings, starting at less than 50 m. above sea level. In borehole 77, about 18,000 to 20,000 gals, per hour. In the Upper Chalk.—In the west the strata are very porous, and contain salt water, so that it would seem to be necessary to sink shafts by the wet process. In the Nouvelle beds the strata at the base soak up water. In the Herve beds brine and warm springs are occasionally found. In the Trias.—Brine spring at Eelen. In the Carboniferous.—Water issuing from a fault was met 'with in the Beeringen borehole; and therefore influxes of water must be reckoned with in the Campine coal measures, as in many places in Westphalia. Up to the present the following six double shafts have been commenced (all by the freezing process), the depths to which they had been sunk by the end of June 1914 being given in parentheses :—Andre Dumont sous Asch (464 and 263-15 metres), Les Liegeois (180 metres), Helcheren (in the freezing stage only), Winterslag (456 and 373-25 metres), Beeringen (396 and 176 metres), Sainte Barbe (102-75 metres). Since that date, how- ever, several of them are stated to have reached the coal measures. The depth to which freezing was effected in relation ( ±) to the surface of the carboniferous was : Andre Dumont, + 125 metres; Les Liegeois, ± 0; Helchteren, — 17 metres; Winterslag, + 58’8 metres; Beeringen, -f- 126 and 132 metres; Sainte Barbe, — 25 metres; so that in two cases it was found necessary to freeze right down into the coal measures. In any event, it will have to be taken into considera- tion, in sinking shafts in the Campine, that water occurs in all the sandy or fissured horizons which occupy a large proportion of the total section, and that, conse- 555.00 51 (★¥!)' 33/.00 t 755.00 5 3 0.00 quemly, difficulties may arise throughout the entire thickness of the cover rock. Geological Age and Classification of the Campine Coal Measures. Fourmarier and Renier, in particular, occupied them- selves with the geological age of the Campine basin. They proceeded on the assumption that with very few exceptions, the flora in the various English districts, the Valenciennes district and the Ruhr basin are identical. For the North-West of Europe it is customary to distinguish between the Stephanian (Ottweiler beds) in which Pecopteris, Odontoptcris and Calipteridce predominate; and the Westphalian : C zone, with Dictyopteris sub-Brongniarti, Neuropteris tenui- folia, etc.; B zone, with Lonchopteris Bricei; and A zone, with Neuropteris Schlehani, Sphenopteris Hoeninghausi, etc. The Campine borings have not revealed a single type specially characteristic of the Stephanian, but only plants belonging to the Westphalian, so that the section of the carboniferous of the Campine basin must extend at least into the upper Wesiphalian. On the other hand, there is an absence of Neuropteris Schlehani, and all but indistinct remains of Sphenopteris Hoeninghausi, so that the lower horizons of the Westphalian have not been identified with any certainty. All the' fossils discovered in the Campine have also been found in the Liege and Hainaut basins, thus justifying the conclusion that the two coal deposits north and south of the plateau of Brabant are of the same age, and that the coals of the Campine are of the same period as those of the coal fields of England, Northern France, and Westphalia. Since the only information available is that afforded by borehole sections, the classification of the productive coal measures of the Campine is extremely difficult; and the numerous workers who have gone into the matter have come to very different conclusions. Basing on the plant remains, Fourmarier and Renier divide the carboniferous of the Campine as shown in Table I.