72 



Newer Tertiaries. 

 The surface soils of the less elevated tracts along the coast 

 and in the interior are recent deposits, formed by the disin- 

 tegration of the rocks of the locality. They consist either of a 

 sandy loam or else an adhesive clay, A 7 arying from sis to fifteen 

 inches in thickness (figs. 2 and 3). Limestone concretions 

 succeed these, varying in thickness from one to eight feet, and 

 consist of a more or less intimate aggregation of sub-globular 

 bodies from the size of a pea to that of billiard balls, aud 

 larger. Where closely cemented they form the so-called 

 " Limestone crust " of the lower parts, sometimes apparent on 

 the surface, where the soil has been removed by atmospheric 

 agencies (fig. 2 under " Ardrossan "). Another kind of lime- 

 stone, viz., Travertine, is found on the summit of the hills and 

 on their sides, but always in situations nearly horizontal. It 

 occurs in thin layers, denser, heavier, and darker in colour than 

 the preceding, and frequently containing numerous fragments 

 of the oldest rocks of the neighbourhood, sometimes sharp- 

 edged and sometimes rolled. (Figs. 2 and 3 centre, and on hill 

 top.) Both limestones seem to be of recent formation, but the 

 latter appears to be the older on account of its greater density, 

 and formed probably under different .conditions, for example, 

 greater abundance of water. In neither have any fossils being 

 detected. 



Pleistocene. 

 The section of the coast cliffs (fig. 2) shows below the con- 

 cretionary limestone a series of clays and gravels, containing 

 pebbles of granite, hornblende, mica slate, sandstone, &c, and 

 also of the Tertiary grits with their characteristic fossils. 

 False bedding is observable throughout, proving a turbulent 

 state of affairs during deposition. Amongst the adhesive clays 

 of this series thin, parallel bands of white pipeclay appear 

 frequently, to the number of three or four, and are persistent 

 for considerable distances. The total thickness of this stratum 

 may be estimated as ranging between twenty and thirty feet. 

 It is, for reasons indicated above (principally as containing 

 pebbles and fossils of Older Tertiary rocks), certainly of more 

 recent origin, but whether it forms an upper member of the 

 Middle Tertiaries or. be of Post-Tertiary origin, is uncertain, as 

 no fossils have been observed. 



Older Tertiaries. 

 Ardrossan Clays and Sand-rock. — The stratum underlying the 

 preceding (apparently conformably) consists of variegated red 

 and white arenaceous clays and sand-rock, interstratified with 

 gravel bands of very characteristic aspect. For this reason 

 they are designated " Ardrossan clays " in the accompanying 



