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EXPEDITION  TO   THE
semon, without bringing together limestones, which in Europe at least, are found of very different ages, unless we adopt the opinion that this oolite is subordinate to the mag-nesian limestone. This we are disposed to do, as we have no reason to believe that the formations of the Mississippi are superior to those of the Wassemon, or that they are separated by the new red sandstone formation; if we could venture to express an opinion, where much doubt really exists, we would say that the oolite was of the same age as the asche, or pulverulent limestone, and that it probably I constitutes merely an accidental modification of the mag-' nesian limestone similar to that observed "at Hartlepool on the coast of Northumberland, where a stratum of hard white oolite exists, the grains composing it being about the size of a mustard seed," and similar to the oolitic varieties which Mr, Freiesleben observed sometimes, though seldom, in the rauchwacke.
If in the rude and unsatisfactory sketch which we have presented of these formations, we have thrown any light upon a doubtful and obscure point, we doubt not we shall be excused, by the experienced geologist, for the apparent contradictions which we may have revealed. Our object has been to state the facts as they came under our notice, and without any intention to establish a connection between the formations of Europe, and those which we have described. If the facts militate against observations made abroad, we must regret it; but we have only stated them as they have appeared to us. Our opinion remains, however, unchanged, that whenever these observations shall be repeated under more favourable circumstances, the difficulties will vanish, and the analogy between the formations of Europe and ours, will appear still greater; a due allowance being of course made for those differences which