1845.] AUSTEN ON THE COAL BEDS OF NORxMANDY. 3 



The character and general aspect of beds associated with coal, of 

 whatever age, from the oldest to the most recent, are so strikingly 

 uniform, that it is a waste of time to attempt to define the age of any 

 given deposit by means of such comparisons. All considerable 

 masses of coal, of every period, seem to have been formed under 

 like conditions ; conditions which have been local, and only a little 

 less so at the period of the true coal-measures, than at previous and 

 subsequent ones. 



But, although independent of the great mass of older rocks of this 

 part of France, the coal strata of Littry might still belong to the 

 true coal-measures. At the time when I first doubted the accuracy 

 of this reference, I had no means of inquiring how far the evidence 

 from the vegetable remains had fixed their age. This I have since 

 been able to do, and the result is in strict accordance with that de- 

 rived from other considerations. Remains of plants are certainly 

 very rare at this place ; but I did not expect to find that it had only 

 afforded two species to M. A. Brongniart's great work on fossil 

 plants, namely Calamites Liickowii, var. /3. p. 124. pi. 16. f. 2, 4 ; 

 and Calamites cruciatus, p. 128. f. 19. 



On the other hand, as has been observed by M. Dufrenoy, coni- 

 ferous wood is found in abundance, — a character which is very usual 

 in the lower beds of the new red sandstone series, and one which I 

 have frequently remarked in the west of England. But the nume- 

 rous impressions of ferns, so characteristic and abundant in the 

 shales of every true coal-field, are wanting, together with all the 

 other usual forms, — Lepidodendron, Stigmaria, &c. &c. The new 

 red sandstone of all this part of France is equally rich in fossil-wood, 

 and M. de Gerville particularly pointed out to me that of Monteburg, 

 to the east of Valognes, as containing large branched trees. 



In the absence, then, of any direct evidence as to the age of the 

 Littry coal-field, the position and mineral character of its associated 

 beds are entitled to consideration. Now these correspond exactly 

 with those of the new red sandstone groupjaeneathyand at the edge 

 of which formation the mines are situated C It has never been pre- 

 tended that there was any want of conformity between the beds 

 which surmount the coal and those which immediately contain it ; 

 on the contrary, they seem to form a consecutive series, and cannot 

 be separated into true coal-measures, and overlying new red sand- 

 stone (as cases in this country might suggest), but belong entirely 

 to the latter period, of which they form the base, the coal seam 

 being a subordinate bed. 



It is unnecessary to enter into like details with respect to the se- 

 veral other localities in which coal has been found or is now worked, 

 in the departments of Calvados and La Manclie ; as for instance at 

 Moon, a few miles west of Littry, and at Plessis, since the coal oc- 

 curs everywhere under precisely similar circumstances of position 



* M. Alex. Brongniart remarks on the resemblance of the beds wbicli surmount 

 the coal to his " jjsephite," or lower red sandstone, bnt adds, ** ce rapprochement 

 ne paroit pas differer de celui que M. llcriiult etablit entre {•ettc ruche, et le grcs 

 rouge ancien." — Tableau des Terrains, p. 276. 



B 2 



