For instance, there is at the base of the upper portion of the cretaceous system a certain hard, often pebbly, and highly coloured band, which, notwithstanding its great departure from the popular type, is nevertheless styled in geological language the "Red Chalk." This stratum, the subject of the present paper, nowhere forms a mass of any great thickness or extent; perhaps if thirty feet be taken as its maximum of thickness, four feet as its minimum, and one hundred miles as its utmost extent in length, the truth will be arrived at. It may be said, also, to be peculiar to England, for the _Scaglia_, or Red Chalk of the Italians, has little in common with that of our country. The two differ widely in appearance, in situation, and in fossils. The first view of the seam in the north is to be obtained about six miles north-west of Flamborough Head, in Yorkshire, near the village of Speeton, where its structure, dip, and general appearance can be remarkably well studied. Speeton is a small village, a place of no great note in the business-world, yet of much fame amongst the lovers of geology, inasmuch as in its neighbourhood there are several interesting formations, to one of which--the Speeton clay--it gives a name. In these days of rapid travelling, the village has the great convenience of a railway-station, from whence the cliffs below can be reached without the slightest difficulty. [Illustration: Lign. 1.--Map of Part of Yorkshire, Lincolnshire, and Norfolk, showing the Outcrop and Range of the Red Chalk.] As I wish to conduct the members of the Association to the Red Chalk _in sitû_, let us suppose that, starting from some locality near the Hull and Scarborough Railway, we have taken tickets for Speeton station, and have in due time arrived at that latter place. On alighting from the train we must direct our steps to the houses in front, and then inquire the way to the sea-shore, above which we shall be standing at some considerable height--say four hundred feet. We shall be told to walk by the church, to turn to the right along a little lane, and then to look for an obscure path which passes across the fields. We shall soon afterwards, being on high ground, be able, by the light of nature, to find a way down to the sands below.