24 The Ash Bed at Meriden. 



The ash bed is interesting enough in itself, but its value is still 

 greater in the evidence that it gives in regard to the general history 

 of the region. I gladly avail myself of the invitation of the Meri- 

 den Scientific Association to write a few pages about it, from this 

 point of view. It is like a monument whose value is less in record- 

 ing the facts of its construction than in recalling the events that it 

 commemorates. 



The ash bed is a good teacher on two matters of importance in 

 the geological history of Meriden. It tells much in regard to the 

 conditions of accumulation of the series of deposits that form the 

 rock foundation of the country, and it tells something also about 

 the deformation that the mass has suffered since its materials were 

 brought together. 



All observers are familiar with the reddish sandstones, shales and 

 conglomerates that make the bed-rock of the country, and with the 

 sheets of trap that form the ridges. In this part of the valley the 

 trap does not occur in the form of dikes, but as sheets, in just the 

 same interbedded position that beds or sheets of conglomerate might 

 have. The question then arises, how did these sheets of trap attain 

 their position between the beds of sedimentary deposits, and to this 

 there are two answers. The trap sheets may have been shoved or in- 

 truded between the sedimentary rocks after the latter had been made, 

 or they may have been poured out as lava flows during the making 

 of the sedimentary series. In the first case they are called intrusive 

 sheets, and are known to be such by the signs of baking that they 

 produce on the over-lying beds, and by the dense texture at their 

 upper surface, where they were under great pressure of the rocks 

 above, as well as by the occasional appearance of small offshoots 

 which cut the adjacent strata. In the second case, they are called 

 extrusive, and are known to be such by the appearance of various 

 features characteristic of lava flows, such as vesicular or scoriaceous 

 upper surface of loose texture, by their association with ash beds, 

 and by the occurrence of their fragments in sandy or muddy deposits 

 lying near their margin or laid upon their surface. The two cases 

 should be clearly conceived in order that the real value of the Mer- 

 iden ash bed, as a point of evidence in the history of the valley, 

 may be appreciated, and that it should not be regarded merely as 

 a locality for collecting specimens. With these points in mind, the 

 ash bed takes on a new meaning. We may see it, not simply as an 

 outcrop in the face of a bluff, but as the present edge of a sheet or 

 bed, of which much still remains under ground, not j^-et reached by 

 the destructive forces of the weather, but of which another large 



