In the normal order of geological strata, the whole series of cretaceous formations have to be passed through before reaching the Oolite formation, of which the Kimeridge clay forms almost the upper layer. But at Woodhall and the surrounding district the whole of this series of rocks and soils is wanting. Their absence is eloquent, and tells a tale of widespread destruction. Standing near the Tower on the Moor we can see in the distance, stretching from north-west to south east, the range of hills called the “Wolds,” which, with a “cap” of marls, or sandy and flinty loams, are composed almost entirely of chalk; from them, near Cawkwell Hill (the hill _par excellence_ of chalk), comes the water supply of Horncastle and Woodhall. They extend for a length of some 45 miles, with a width of some six miles to eight. The actual depth of the chalk is not exactly known, but a boring made through it, near Hull, reached the Oolite beneath at 530ft. We may perhaps, therefore, put the average at 500ft. {94a} Doubtless, at one period, this cretaceous formation extended over the whole tract of country, but southward and westward from the foot of the present wolds it has since been swept away. And this must have taken place before the glacial period, because the glacial boulder clay lies upon the Kimeridge clay, which normally underlies the chalk. Mr. Jukes Brown (“Geological Journal,” No. 162, p. 117) says: “The Boulder clay is bedded against the slope of the chalk, shewing that this escarpment had retired to its present position in pre-glacial times.” By what precise process this was effected must be left to our savants to decide; but the remarkable fact remains, that a solid stratum, or rather series of allied strata, from 500ft. to 1,000ft. in thickness, has, by one process or another, been wiped out of existence, over the large area now coated by the Kimeridge clay. Through ages of enormous length the chalk was forming as the bed of a sea; a deposit consisting of inconceivable myriads of beautiful minute shells, mainly of the foraminifera, which can be detected by the microscope; and its destruction probably occupied as long a period as its formation. Mr. Jukes Brown, whom I have just quoted, says: “The Wold hills must have been, in some way, exposed to a severe and long-continued detrition, when erosive agencies were very active.” Active, indeed, they must have been, to efface from an area so extensive a solid formation from 500ft. to 1,000ft. in thickness. And this boulder clay, as Mr. Jukes Brown further observes, has forced its way up the sides of the chalk, in places, to a height varying from 300ft. to 400ft. The Oxford clay, which lies next below the Kimeridge, is a deep sea deposit, dark blue, with brown nodular stones; some of the fossils found in it are Nucula Ornata, Ammonites Plicatilis, A. Rotundus, Cucullæa, Gryphæa Dilatata, Leda Phillipsii, Annelida Tetragona, and A. Tricarinata, Avicula inequivalvis. {94b}