The idler picking up pebbles on the sea-shore, and the geologist breaking stones in a gravel-pit, frequently meet with banded flints, which display their markings like a painting on the smoothly fractured internal surface, or, in other cases, in the form of lines more or less deeply engraved on the exterior by the action of the weather. The bands seen in section are often accompanied by discolorations of fanciful shape, in which imaginative people find pictures of their friends and others.

Ely stands on a hill extending somewhat beyond the city as a ridge to the north; and a mile north-east of the Cathedral, at a spot variously named Roslyn or Roswell Hole, its flank is reached at a well-known pit, where the Kimmeridge Clay is dug for mending the river-banks; and the excavation shows some Boulder-clay and Chalk. What the relative positions and relations of these latter deposits may be has been long disputed; some holding that the Chalk is there in sitû, let down by a fault; others maintaining that it is merely such a drifted mass, included in the Boulder-clay, as those which form so strange a feature in the Drift of the Norfolk Coast.† Professor Sedgwick has long been convinced that this latter view is a groundless hyothesis; for when the railway was made from Ely to Lynn, it exposed at about 100 yards off a section showing Kimmeridge Clay and Chalk side by side, and Boulder-clay between them; so the conclusion inevitably followed that there had been a great fault; letting down the Chalk for at least two or three hundred feet. This section was still to be seen in the spring of 1860, when I examined it. The faulted faces of both stratified formations were perfectly erect, parted by a column of Boulder-clay, some twelve feet wide, which from a distance looked like a basaltic dyke.

It is indended in this paper to present a general outline of the Laurentian Formation under the heads mentioned in the above title; dwelling principally on the latter clause, its residuary elements of life, or, in other words, on those mineral substances, contained within it, which at some earlier period have been the constituents of organic bodies. This formation, or system of rocks, which have been called ‘fundamental,’ has of late years very generally received the name of ‘Laurentian,’ a geographical denomination, taken from the country (Laurentide or Laurentian Mountains) in which it has been well studied, and where it exists in vast force. An assemblage of metamorhosed rocks may usually br considered ‘Laurentain,’ when over great spaces (with or without the intervention of the Huronian and Cambrian rocks) it underlies discordantly beds more or less fossiliferous, named ‘Primordial’ in Bohemia, ‘Lingula-flags’ in Wales, ‘Potsdam Sandstone’ in North America.