406 G. H. Kinahan — Formation of Ravines. 



The upper division of the sandstone layer, or the Fucoid sandstone 

 proper, is not so poor in fossils as has hitherto been supposed. In 

 an earlier memoir^ I have mentioned the discovery of a Lingula at 

 Djupadalen near Karleby. During the last summer I searched in 

 vain for the same species, but in place of it I collected several 

 specimens of another Lingula. Among the specimens obtained not 

 one is quite complete, and they exhibit no decisive generic characters. 

 The rather singular sculpture of the shell however is admirably well 

 preserved, and on that account the species may be named Lingula (?) 

 favosa. The shell is depressed and has almost the form of a sector 

 of a circle, somewhat exceeding a quadrant ; its length is about 5 

 millimetres, the breadth being about 6 millimetres. The anterior 

 half of the shell bears some sharp lines of growth and a few 

 punctse, but otherwise it is smooth. Behind the middle there 

 follows a space closely beset with small excavations. At the very 

 apex, which in all the specimens is more or less damaged, the shell 

 seems again to be smooth. The colour, at least outside, is of a 

 whitish blue. 



EXPLANATION OF THE PLATES. 



Plate XI. Figs. 1 and 2, Lingula monilifera, n. 



„ Figs. 3 and 4, Eophyton Linnceanum, TorelL 



Plate XII. Eophyton Linnceanwn, Torell. 

 Plate XIII. Eophyton Torelli, Linnarsson. 



V. — On the Fobmation of Eavines by Eecent Drift 



AcCUMUIiATIONS. 

 By G. Henry Kinahan, M.E.I.A., etc. 



IT is not unusual in drift deposits, banked on hill slopes, to find 

 a deep cut occupied by a very minute stream. These cuts or 

 ravines are supposed to be due to the streams ; having been excavated 

 by them in the banks of drift. If a ravine of this class is formed in 

 one of the older drifts — namely, the Boulder-clay-drift or the Moraine- 

 drift — it must apparently have been cut by a stream, but much of the 

 drift banked on hill slopes is quite recent ; that is formed by meteoric 

 abrasion, and being added to at the present day. In these recent 

 drifts, ravines are of common occurrence, and I would suggest that, 

 instead of the stream cutting its ravine, meteoric abrasion has heaped 

 up the banks, and the only action capable of being done by such a 

 stream, is to keep its channel clear. Such accumulations of drift are 

 very frequent in association with Maums, or connecting gaps across 

 mountain-ranges, and there are always ravines in the banks, — yet 

 by no arrangement of the water-supply, could streams be formed 

 that would have the power to excavate them. In the accompanying 

 sketch of Maumgeeha, Yar-Connaught, there is a maum, below which 

 is a recent drift-bank with a ravine and its accompanying stream. 

 None of the surface drainage of the hills on either side of the maum 

 can get into the stream, it being fed by a spring, while the surface 

 drainage of the mountains flows as represented by the arrows, and 



3 Bidrag till Vestergotlands Geologi, Ofvers. af K. Vet. Akad. Forh. 1868. 



