Scottish Geographical Magazine ISSN: 0036-9225 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/rsgj19 A bathymetrical survey of the fresh‐water Lochs of Scotland Sir John Murray K.C.B., D.Sc., F.R.S. & Late Fred P. Pullar F.R.G.S., F.R.S.E. To cite this article: Sir John Murray K.C.B., D.Sc., F.R.S. & Late Fred P. Pullar F.R.G.S., F.R.S.E. (1901) A bathymetrical survey of the fresh‐water Lochs of Scotland, Scottish Geographical Magazine, 17:3, 113-128, DOI: 10.1080/00369220108733231 To link to this article: http://dx.doi.org/10.1080/00369220108733231 Published online: 27 Feb 2008. Submit your article to this journal Article views: 8 View related articles Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=rsgj20 Download by: [University of Cambridge] Date: 19 June 2016, At: 19:17 THE SCOTTISH GEOGRAPHICAL MAGAZINE. A BATHYMETRICAL SURVEY OF THE FRESH-WATER LOCHS OF SCOTLAND. By Sir JOHN MURRAY, K.C.B., D.Sc., F.R.S., and the late FRED. P. PULLAR, F.R.G.S., F.R.S.E. PART II. THE REMAINING LOCHS OF THE FORTH BASIN. INTRODUCTION. PART I. of this work, dealing with the lochs of the Trossachs and Callander district, viz., Lochs Katrine, Arklet, Achray, Vennachar, Drunkie, Lubnaig, Voil, and Doine, was published in this magazine in April 1900.1 This second part treats of the remaining lochs of the' drainage basin of the Forth, viz., Loch Chon, with Lochan Dubh, Loch Ard, and Lake of Menteith in Perthshire, and Loch Leven in Kinross-shire. The methods and apparatus used were the same as those described in Part I., all the soundings having been taken from rowing-boats with the F. P. Pullar sounding-machine. , MAI>S AND ILLUSTRATIONS. Downloaded by [University of Cambridge] at 19:17 19 June 2016 The general map of the district published in Part I. includes the lochs now treated of, except Loch Leven. The four maps illustrating this part show the depths in each of the lochs under consideration, on the scale of three inches to the mile (1:21,120), most of the soundings taken during the survey being given in feet. The intervals between the contour-lines of depth are indicated by different shades of blue, and the intervals between the contour-lines of height of the neighbouring country by shades of brown. Plate I. shows Loch Chon with Lochan Dubh, the contour-lines of depth being drawn in at 25, 50, and 75 feet. 1 Vol. xvi. pp. 193-235, with seven coloured maps. VOL. XVII. - I 114 SCOTTISH GEOGRAPHICAL MAGAZINE. Plate II. shows Loch Ard, the contour-lines of depth being drawn in at 25, 50, 75, and 100 feet. Plate III. shows Lake of Menteith, the contour-lines of depth being drawn in at 10, 25, 50, and 75 feet. Plate IV. shows Loch Leven, the contour-lines of depth being drawn in at 10, 20, 50, 70, and 80 feet. In addition to the maps there are four woodcuts in the text, illus- trating the character of the scenery around the lochs. DEPTHS OF THE LOCHS. Loch Chon.—There are two lochs in Perthshire bearing this name, the one a little loch in the parish of Blair Athole. The Loch Chon now [Photo bij G. W. Wilson. FIG. 1.—Loch Chon. under consideration lies to the south of Loch Katrine, and trends in a north-west and south-east direction. It lies at a height of 296 feet Downloaded by [University of Cambridge] at 19:17 19 June 2016 above sea-level, and the river into which it flows expands, a little distance to the south-east, into the small loch, Lochari Dubh or Loch Dhu, the surface of which is-10 feet lower. Loch Chon is over If miles in length, and the greatest width is about one-third of a mile. The mean breadth, obtained by dividing the area of the loch by its length, is a quarter of a mile, being 15 per cent, of the length. Its waters cover an area of about 277 acres, or less than half a square mile, and it drains an area about 14J times greater, or nearly 4000 acres (nearly 6| square miles). The number of soundings taken in Loch Chon was 157, the greatest depth observed being 75 feet. The mass/of water contained in the loch is estimated at 358,000,000 cubic feet, and the mean depth BATHYMETUICAL SURVEY OF FRESH-WATER LOOHS OF SCOTLAND. 115 at over 29 feet, or 39 per cent, of the maximum depth. The length of the loch is 120 times the maximum depth,and 305 times the mean depth. Loch Chon is irregular in. outline, and the contour-lines are also irregular. The deepest part of the loch (i.e. exceeding 50 feet) forms a long, narrow depression, situated approximately in the centre of the loch but closer to the western than to the eastern shore, about seven-twelfths of a mile in length with a maximum width of over one-sixth of a mile. The maximum depth, 75 feet, was found comparatively very close to the western shore, being in fact only about 130 yards distant; this gives a slope of almost 1 in 5, and a similar steep slope is indicated by the near approach to the shore of the contour-lines for a considerable distance along the western side of the loch. The slope from the eastern shore is, generally speaking, more gradual. The 25-feet depression is divided into two portions by the rising of the floor of the loch about a quarter of a mile from the southern end. The maximum depth in the smaller southern depression is 49 feet. The larger 25-feet depression, separated from the smaller one by an interval of about one-eighth of a mile, is over 1^ miles in length, approaching close to the north-western end of the loch, with a maximum breadth of three-eighths of a mile. This larger depression is very irregular in outline, occupying nearly the full width of the loch towards the centre, while a short distance farther south there is a narrow constriction in the vicinity of the Heron Islands. The area of the bottom between the shore line and the 25-feet contour is about 119 acres, or 43 per cent, of the total area of the loch ; that between the 25- and 50-feet contours is about 127 acres, or 46 per cent., and that deeper than 50 feet is about 32 acres, or 11 per cent. Lochan Dubh.—This little basin is one-fifth of a mile in length, and less than one-sixth of a mile in maximum width. Its waters cover an area of about 11J acres, and it drains an area eighteen time,s greater, or about 205 acres. The mean breadth is less than one-tenth of a mile, or 45 per cent, of the length. Twenty-five soundings were taken in Lochan Dubh, the maximum depth observed being 41 feet. The cubic mass of water is estimated at 586,000 cubic feet, and the mean depth at nearly 21 feet, or 50 per cent, of the maximum depth. The length of the loch is 28 times the maximum depth, and 56 times the mean depth. Lochan Dubh is very simple in construction, shoaling on all sides down to the deepest part. As in Loch Chon the slope seems to be much Downloaded by [University of Cambridge] at 19:17 19 June 2016 steeper off the western than the eastern shore, a cast of 35 feet having been taken comparatively very close to the west side. The water shallows where the loch narrows a little above the outlet, a depth of 3 A feet being found where the bottom is covered with reeds. The area of the bottom between the shore and the 25-feet contour-line is about 7 acres, or 60 per cent, of the area of the loch, and that deeper than 25 feet is nearly 5 acres, or 40 per cent. Loch Ard.—Loch Ard receives the outflow from Lochan Dubh and Loch Chon; it trends in an east and west direction, sending out one prolongation to the south and another to the east. Its level is 105 feet above the sea. It is over three miles in extreme length, including the eastern prolongation, but the body of what may be called the loch proper is about 2 J miles in length : from the head of the loch to Helen's Eock. 116 SCOTTISH GEOGRAPHICAL MAGAZINE. The greatest width, measured from the extremity of. the southern pro- longation to the northern shore of the loch, is over one mile, the mean breadth being two-fifths of a mile. Its waters cover an area of over 600 acres (nearly one square mile), and it drains an area of more than ten times greater, or about 6250 acres (9f square miles). The number" of soundings taken in Loch Ard was 308, the maximum depth being 107 feet. Thus the deepest part of Loch Aid dips two feet below sea-level. The cubic mass of water contained in the loch is estimated at 1,150,000,000 cubic feet, and the mean depth at nearly 44 feet, or 41 per cent, of the maximum depth. The length of the loch is 113 times the maximum depth, and 277 times the mean depth, Loch Ard proper forms a comparatively simple basin, shoaling from {Photo ty J.