Freshwater Limestone in Forfarshire, Sgc. 89 



Names of Montagu. Names of Lamarck. 



15. Turbo fontinalis Valvata piscinalis. 



-16. cristatus • cristata. 



17. Helix tentaculata Paludina impiira. 



18. Patella fluviatilis Ancylus fluviatilis. 



19. " lacustris ■ lacustris. 



20. Tellina cornea Cyclas cornea. 



21. Cardium amnicum obliqua. 



In the marl occur branches and trunks of trees but httle altered, and fre- 

 quently encircled with whitish calcareous concretions, several inches thick, 

 consisting of the same substance as the nodules before mentioned. Both in 

 the marl and peat have been found the bones of many animals. Mr. Daman 

 of Romsey has formed a collection of some of these remains, among which 

 Professor Buckland recognised the bones of the stag, roebuck, beaver, pig, 

 and ox. Springs are common in these alluvial tracts. The marl occupies 

 irregular spaces, surrounded, and often abruptly terminated, by peat. The 

 spots in which it is found are usually elevated some feet above the level of the 

 alluvial flat of the Test, and are called by the workmen, from that circumstance, 

 "malm-knolls." There are places where the marl is overlaid by peat, and 

 where the two are intermixed, forming what the workmen call black malm 

 and white peat. 



Of these facts the following explanation may be offered. — The low grounds 

 by the side of the Test were first covered by peat, which the river occasion- 

 ally overflowed, carrying with it drift timber and the bones of such animals 

 as by diff'erent casualties had perished in the water or within reach of floods. 

 In different parts of these marshes, however, there remained pools of still 

 water, in which freshwater testacea subsisted. The numerous land-shells which 

 are found mixed with the aquatic species, belonged to testacea inhabiting 

 the borders of the river, which, when high, still passed into these lakes, and 

 drifted in occasionally, together with the shells, the wood and peat now some- 

 times found intermixed with the marl. At length the basin was filled up with 

 shell-marl ; testacea could no longer exist there ; and in some places a small 

 increase of peat took place on the surface of the marl. Lastly, the river 

 covered in some parts (as at Ashley Meads) both the marl and the peat with 

 alluvial clay, without any admixture of shells or of marly matter. This last 

 operation was in all probability the result of several floods, during which the 

 waters rested some time on these flats ; so that the argillaceous sediment some- 

 times attained the thickness before mentioned. To account for the present 

 elevation of the marl above the banks of the pools in which it was formed, 

 Mr. Daman suggests, that the peat when no longer on the increase, after be- 



VOL. II, — SECOND SERIES. N 



