THE OLD RED SANDSTONE.

45

Atd this, too, with opportunities of observation at everystage which can be shared with him by only the gentlemanof fortune who devotes his whole time to the study. Nay,in some respects his advantages are superior to those of theamateur himself. The latter must often pronounce a forma-tion unfossiliferous when, after the examination of at most afew days, he discovers in it nothing organic ; and it will befound that half the mistakes of geologists have arisen fromconclusions thus hastily formed. But the working man,whose employments have to be carried on in the same for-mation for months, perhaps years, together, enjoys better op-portunities for arriving at just decisions. There are, besides,a thousand varieties of accident which lead to discovery,—floods, storms, landslips, tides of unusual height, ebbs of ex-traordinary fall; and the man who plies his labour at allseasons in the open air has by much the best chance of pro-fiting by these. There are formations which yield their or-ganisms slowly to the discoverer, and the proofs which estab-lish their place in the geological scale more tardily still. Iwas acquainted with the Old Bed Sandstone of Boss andCromarty for nearly ten years ere I had ascertained that itis richly fossiliferous,—a discovery which, in exploring thisformation in those localities, some of our first geologists hadfailed to anticipate : I was acquainted with it for nearly tenyears more ere I could assign to its fossils their exact placein the scale.

In the following chapters I shall confine my observationschiefly to this system and its organisms. To none of theothers perhaps, excepting the Lias of the north of Scotland ,have I devoted an equal degree of attention ; nor is there aformation among them which, up to the present time, hasremained so much a terra, incognita to the geologist. Thespace on both sides has been carefully explored to its upperand lower boundary ; the space between has been suffered to