NATURAL HISTORY SOCIETY OF GLASGOW. 151 



PAPERS READ. 



I. — On an Ancient Eiver Course at Auchinlea, Parish of Shotts. 

 With a Plate. By Mr James S. Dixon. 



My attention was first directed to the ancient river course which 

 forms the subject of these remarks about the end of the year 1865. 



In the course of working the main coal seam of the Lanark- 

 shire coal series by the Midhill Pit, the workings were interrupted 

 by what the miners thought a nither novel dislocation, as it was 

 composed of water-worn stones and sand, which indicated a slip 

 of an unusual type. As the workings were then within a short 

 distance of the boundary of the property, nothing was done to 

 prove its actual nature or extent for upwards of a year, when a 

 short exploring drift was driven into it at a point eastward of 

 where it was first touched. This clearly showed it to be the bed 

 of an ancient river, which had washed away the coal and adjoining 

 strata, leaving in their place a deposit of sand, gravel, and stones. 

 I exhibit a plan of the district, on which the river course, as far 

 as explored, is laid down. At the time I have spoken of, the 

 coal had not been begun to be worked to the south, between the 

 supposed line of the river course and the two large upthrow slips 

 which bound the field to the south and west. Two pits have 

 since then been sunk, the workings of which have laid bare 

 the south side of the channel, and two drifts have been driven 

 through it at diff'erent points, which throw considerable light on 

 the subject. 



Fig. 1 is a cross section, shewing the manner in which the 

 channel intersected the strata at point D, where it was cut through 

 by drift No. 1, which was similar to that seen in the short 

 drift first mentioned. In these cases the floor of the drifts were 

 still in the channel, so tliat nothing could be said as to its 

 probable depth. This was clearly defined by drift No. 2, which 

 passes immediately under the bed of the ancient river, as shewn 

 in section by Fig. No. 2, as well as by a bore recently put down, 

 at point A on plan. The depth of the bottom of the bed from 

 the surface, at point B, where drift No. 2 intersects it, is about 

 130 feet, and at point A 114 feet. This latter depth, I think, 

 cannot be in the centre of the channel. The reason of the 

 different manner in which the channel intersects the coal at 



