LAMPLUGH : NOTES ON THE WHITE CHALK OF YORKSHIRE. 
77 
Part II. The Small Faults (' Joint Faults ') of the Chalk. 
A notable feature of tlie Yorkshire Clialk is tlie multiplicitj^ of 
the small faults b}' which it is intersected. These are probably 
everywhere prevalent, but can only be studied in sequence in the 
coast section, and it is also only there that their frequency becomes 
clearly evident. In the detailed examination of the Chalk cliffs my 
attention was necessarily arrested by these faults, as they caused 
some difficulty in measuring the various strata. It then occurred to 
me that although the displacement caused by any single fault 
rarely exceeded a foot or two, if their effect were cumulative their 
aggregate value might be very considerable. To test this ])oint I 
commenced, while measuring the strata, to note down every fault I 
could detect in a given area, with the amount and direction of its 
throw. In this manner I collected the details relating to fifty-nine 
such faults occurring in consecutive sequence between Danes Dike 
and South Sea Landing, and eleven more, making seventy in all, to 
the eastward of the South Sea." These details are fully set forth at 
a later page (Appendix B, p. 8G). The observations have been 
combined in the following diagram, in which the number of displace- 
ments and the net total value of dowuithrow, in feet and inches, in 
the various directions are stated. Thus, for example, a reference to 
the appendix will show that there are fourteen faults in all with 
downthrows to the north-eastw^ard, and that their sum gives a 
vertical displacement of 11 feet 1 inch ; and so on. (PI. xvi.) 
This method of analysis has proved that my initial surmise that 
these faults might be cumulative in one direction is not correct. I 
imagined that a dislocation of low hade coming up from more con- 
sistent strata into a rock so full of joints and fissures as the Chalk, 
might be split up into numerous branches and dispersed over a con- 
siderable breadth of ground. But in this case the analysis would 
have shown a strong preponderance of downthrow towards a definite 
quarter ; whereas it will be seen from the diagram that the displace- 
ments are so evenly dispersed that if the dial be divided along the 
* Another set was measured in the cliff between Sewerby and Danes Dike, 
but the record has been misplaced, and I am therefore unable to incorporate 
it in these notes. 
