It is now well known, says Mr. Farey, to many observers in geology, that the clay strata on which the metropolis is situated, extend north-eastward through Essex, Suffolk, and Norfolk, and are incumbent on the great chalk stratum, which reaches from the Isle of Wight to Flamboro’-head; and that these, as well as many subjacent strata that are known, dip in general to the south-east, and basset out, or appear at the surface in succession, to any one travelling toward the N. W., until he has passed certain strata of lias, clay, and sand. Beneath these, says the author, are found marks of an immense stratum of red marl, which seems (to him) to have extended over all the remainder of the British islands. In this stratum are contained local strata of gypsum, rock salt, sand, micaceous gritstone, &c.: to this stratum also, according to the author, belong the great nodules of slate, green stone, sienite, basalt, &c. that form hills or mountains, intersected by mineral veins, in the western parts of the kingdom. In many parts, however, the red marl itself is no longer found; but instead of it various strata, subjacent to it, have been elevated to a considerable height, and subsequently denudated by the operation of water, as observed by Dr. Richardson, in his remarks upon the basaltic comities of Antrim and Derry in Ireland.