Mr Maclaren on Ancient Beaches near Stirling, 405 



The internal structure of the terrace is shewn at several places, 

 and bears unequivocally the character of a deposit from water. In 

 a quarry near Lecropt Church, the materials are seen to be sand 

 and gravel rudely deposited in strata. At the River Allan sandstone 

 is seen under the bridge, in the water-course, above which all is 

 gravel and clay to the top ; but the gravel is coarse, such as a river 

 subject to floods brings down, and in which stratification is often not 

 apparent. A furlong east from this there is a quarry on the sum- 

 mit, about 5 or 6 yards deep, where three or four beds of gravel al- 

 ternate with as many of sand, all pretty correctly horizontal. The 

 sand and fine gravel shew stratification ; the coarse gravel does not. 

 Half a mile eastward there is a small opening in the wood only four 

 or five yards above the Carse level, where again we find sand and 

 gravel in layers, and there are other openings presenting similar ap- 

 pearances. At the cut made for the railway under the road at 

 Bridge of Allan, the bottom of the terrace was found to consist of 

 the blue boulder clay, inclosing a few rolled and striated boulders 

 from 2 to 3 feet in diameter. This clay, which rose to at least 30 

 feet above the Carso, and was covered with sand, probably forms the 

 lowest stratum of the terrace along a considerable part of its extent, 

 and by its compactness and tenacity may have contributed essentially 

 to its presei-vation. 



The breadth of the terrace at Lecropt Church may be about 200 

 feet. At the mineral well, I found it to be about 900 feet, and 

 tov/ards the east end, within Lord Abercromby's grounds, it must be 

 nearly half a mile. 



That the terrace does not owe its elevation to a nucleus of rock is 

 evident ; for, from Lecropt Church to Causeyhead, a distance of 2 

 miles, though various breaches and openings, 50 or 60 feet deep, 

 exist in it, no vestige of rock in situ is visible, except at the bridge 

 over the Allan, where the sandstone is seen many feet under the 

 level of the Carse. 



Like our present beaches, the terrace, though nearly level, is not 

 rigidly so at every point. In the cross section at the mineral well 

 (section 2), the lowest part of the surface is that at a' next the hill. 

 Beyond this is a slight swell (6') rising 15 or 20 above a\ and melt- 

 ing gradually into the outer portion, which scarcely deviates from a 

 dead level. This outer portion terminates in an escarpment at c\ 

 precisely such as we find in a bank of earth, exposed to the action 

 of a river or the tide. When the sea which deposited this terrace, 

 had sunk to a lower level, and merely washed its foot, the tides bad 

 eaten away, in the course of ages, all that portion which was towards 

 the centre of the valley, leaving this remnant as a witness of the 

 higher level at which the water once stood. 



It is scarcely necessary to say that, in speaking of the sea rising 

 so many feet or yards above its present level^ or subsiding so many 

 feet or yards below it, the expression is put in this form merely to 



VOL. XLI. NO. LXXXII.— OCTOBER 1846. 2 D 



