Vol. 59.] BORING AT CAYTHORPE (LINCOLNSHIRE). 31 



Further evidence may be gathered from the following observa- 

 tions : — 



(a) The waste-heap, representing the uppermost 38 feet of the 

 Upper Lias, contained numerous fossils. Leda ovum was abundant, 

 and one specimen had Discina reflexa attached to it. Ammonites 

 bifrons was also fairly numerous, together with Myacites donaci- 

 formis, and belemnites, and also a large fragment of Ammonites 

 lieterophyllus . 



(b) The fragments of undisturbed clay washed from the samples 

 taken at every few feet of the boring, showed an amorphous con- 

 dition, until a depth of 190 feet had been reaehed. Erom this depth 

 the washed-up fragments had a decidedly laminated appearance, and 

 this was taken to indicate that the paper-shales, which occur at the 

 base of the Upper Lias, had been reached. 



(c) At one time, when the clay held out to so unexpected a 

 thickness, it was thought probable that the boring-rods had passed 

 through a fissure in the Marlstone, but no samples of clay brought 

 up seemed to indicate this, there being neither mica nor sand to be 

 found in the clay above the Marlstone. 



(d) The Marlstone-Rock was of the usual dark greenish-blue 

 colour, and one fragment contained a portion of a shell of Terebratula 

 punctata. 



(e) As soon as the Kock-bed had been passed through, the cha- 

 racter of the clay changed. It was greenish, and both sand}* and 

 micaceous, the sand and mica being in thin layers -jL- inch apart. 

 The sand-grains washed from the clay are very small, being from 

 Too" ^° "2o~o ^ ncn * n their longest diameter, with a very few larger 

 grains mixed with them. The}* consist of sugary quartz, and are all 

 perfectly angular fragments. 



(/) South of the line of section, there is a slight depression in the 

 ground, which terminates with the easterly projecting tongue of Lias 

 seen in plan. There is also a noticeable depression running for 

 about a mile northward, and passing through the position of Well 

 No. 5. This seems to indicate that the mass of Limestone lying west 

 of this depression has broken its back along this line, and has a 

 tendency to slip westward. 



(g) Finally, after sinking Well No. 2, which is called the Engine- 

 house Well, a heading was driven for several yards south, it being 

 at the junction of clay and limestone ; and I am informed by 

 Mr. Smith, engiDeer to Mr. Lubbock, that the only flow of water 

 coming into this well and heading is from two small fissures on the 

 east side, showing that the flow of water is with the slipped 

 limestone. 



Postscript. 



[It seems to be thought possible that a north-and-south fault 

 exists west of Boring No. 5. In relation to this there are two facts 

 which appear to indicate that the continuity of the Marlstone has 

 not been broken by a fault on the west side of the boring : — 



(1) The inclination of the roadway west of A (see fig. 1, p. 30) 



