NATURAL HISTORY SOCIETY OF GLASGOW. 35 



the time to which our oldest boulder clays are referred, and the 

 utter want of fossils in them is therefore not to be marvelled at. 

 How long this Arctic condition lasted we cannot even guess, but 

 we know that at length its rigour was slackened, and over land 

 and sea the frosty grip of a Polar winter loosened, and life began 

 to multiply in, and enliven, both. This was the time to which the 

 fine laminated clays of tlie Clyde valley are generally referred. 

 During this probably lengthened period numerous colonies of 

 Arctic shells migrated southwards, and filled our bays and firths 

 with all the various genera and species whose remains we now 

 find so plentifully in these clays. Kilchattan Bay was one of 

 these localities, and in its clay-fields we have evidence that its 

 waters teemed with life of every grade and character, proper to 

 the conditions of the place and time. That these conditions were 

 exceedingly tranquil is evident to any one minutely examining its 

 deposits. In Kilchattan the shells are found lying where the 

 animals lived and died, and, if lifted carefully, the shells of each 

 bivalve will be found united; none of them exhibiting signs of 

 travel or wear, showing that the deposit in which they are now 

 entombed was quietly laid down around them. 



The next great geological epoch, that of the Raised Beaches, is 

 well represented in the neighbourhood of Kilchattan. I have 

 closely examined the beach from Kerrylamont on the south-east, 

 to Scalpsie Bay on the south-west, and have observed numerous 

 high cut terraces, along with wide and deep old sea caves. Many 

 of these are so large that cattle find shelter in them from the 

 heat and storms, and people who gather cockles at Kilchattan 

 Bay for the market, often make these caves their dwellings, 

 living in gipsy fashion. 



The section at Kilchattan clay-field is as follows : 



First — The oldest till, or boulder clay, resting on the sandstone 

 rock. 



Second — The finely laminated clay, from 10 to 12 feet in thickness. 



Third — Resting on this clay is a deposit of obscurely stratified 

 clay, about 2 feet in thickness. In this deposit lies the shell-bedj 

 which appears to be only a few inches in thickness. 



Fourth — Above the shell bed is a layer of sandy clay, with 

 neither shells nor stones, 12 to 22 inches in thickness. 



Fifth — Resting on this clay is a mass of stratified gravel and 

 shingle, forming a bank from 5 to 9 feet in depth. 



