. Island life : or, the phenomena and causes of insular faunas and floras, including a revision and attempted solution of the problem of geological climates . oldmoraines across the valley up which it has once seen and examined, these moraines can alwaysbe distinguished almost at a glance. Their position ismost remarkable, having no apparent natural relation tothe form of the valley or the surrounding slopes, so thatthey look like huge earthworks formed by man for pur-poses of defence. Their composition is equally peculiar,consisting of a mixture of earth and rocks of all sizes,
. Island life : or, the phenomena and causes of insular faunas and floras, including a revision and attempted solution of the problem of geological climates . oldmoraines across the valley up which it has once seen and examined, these moraines can alwaysbe distinguished almost at a glance. Their position ismost remarkable, having no apparent natural relation tothe form of the valley or the surrounding slopes, so thatthey look like huge earthworks formed by man for pur-poses of defence. Their composition is equally peculiar,consisting of a mixture of earth and rocks of all sizes,usually without any arrangement, the rocks often beinghuge angular masses just as they had fallen from the sur-rounding precipices. Some of these rock masses often reston the very top of the moraine in positions where no othernatural force but that of ice could have placed them. dHAP. VII THEl GLACIAL SPOCH 109 Exactly similar mounds are found in the valleys of NorthWales and Scotland, and always where the other evidencesof ice-action occur abundantly. Travelled Blocks.—The phenomenon of travelled orperched blocks is also a common one in all glacier. A GLACIER WITH MORAINES. countries, marking out very clearly the former extent ofthe ice. When a glacier fills a lateral valley, its foot willsometimes cross over the main valley and abut against itsopposite slope, and it will deposit there some portion of itsterminal moraine. But in these circumstances the end ofthe glacier not being confined laterally will spread out, no ISLAND LIFE i>aet i and the moraine matter will be distributed over a largesm^face, so that the only well-marked token of its presencewill be the larger masses of rock that may have beenbrought down. Such blocks are found abundantly inmany of the districts of our own country where othermarks of glaciation exist, and they often rest on ridges orhillocks over which the ice has passed, these elevationsconsisting sometimes of loose material and sometimes ofrock
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