These questions, seemingly simple enough, involve what was wont to be one of the greatest problems of geology, and not many years have elapsed since it was solved. The whole surface of the country was observed to be thickly covered with a series of clays, gravels, and sands, often abounding in rounded masses of rock of all sizes up to several yards in diameter. These deposits were seen to cover all the harder rocks, and to occur in a very irregular manner, sometimes heaped up into great mounds, and sometimes entirely wanting. They were evidently the results of no agency visible now, either on the land or around our coasts. They had an appearance rather of tumultuous and violent action, and so it was wisely concluded that they must be traces of the great deluge. The decision had at least this much in its favour, it was thoroughly orthodox, and accordingly received marked approbation, more especially from those who wished well to the young science of geology, but were not altogether sure of its tendencies. But, alas! this promising symptom very soon vanished. As observers multiplied, and investigations were carried on in different countries, the truth came out that these clays and gravels were peculiarly a northern formation; that they did not appear to exist in the south of France, Italy, Asia Minor, Syria, and the contiguous countries. If, then, they originated from the rushing of the diluvian waters, these southern lands must have escaped the catastrophe, and the site of the plains of Eden would have to be sought somewhere between the Alps and the North Pole. This, of course, shocked all previous ideas of topography; it was accordingly agreed, at least among more thoughtful men, that with these clays and sands the deluge could have had nothing to do. Other theories speedily sprang up, endeavouring to account for the phenomena by supposing great bodies of water rushing with terrific force across whole continents, sweeping away the tops of hills, tearing up and dispersing entire geological formations, and strewing the ocean-bottom with scattered debris. But this explanation had the disadvantage of being woefully unphilosophical and not very clearly orthodox. Such debacles did not appear to have ever taken place in any previous geologic era, and experience was against them. Besides, they did not account for some of the most evident characteristics of the phenomena, such as the northern character of the formation, the long parallel striations of the rock surfaces, and the perching of huge boulders on lofty hills, often hundreds of miles distant from the parent rock. Geologists were completely at fault, and the boulder-clay remained a mystery for years.