APPENDIX—GEOLOGICAL SURVEY. 
427 
There are but few things in geological investigations of more 
importance than to be able to distinguish between physical 
conditions peculiar to one period of geological formation and 
those common to many, or to all. We cannot have too deeply 
impressed on our minds the fact, that in entering upon the ex¬ 
amination of these strata, we have to investigate rocks of more 
ancient date, formed in a period vastly remote. We are no 
longer delighted with, the fossil remains with which the lime¬ 
stones of the lead district are crowded. At this period, the 
waters of the primeval ocean rolled over our continent, save 
here and there a narrow strip of land on which life had not 
yet begun. And even the physical conditions of the sea were 
such that life had but just a beginning there. A lonely trilo- 
bite might now and then have been seen lingering near the 
shore, or a tiny little singlo clinging to the rock, but beyond 
this there was no sign of life. This was emphatically the age 
of crystallization and mineral formations ; the highest and most 
beautiful forms of matter before organic forms appeared. 
As we descend the northern dip of this elevation and com¬ 
mence our investigations in these lower and older formations, 
we find that the character of the rock is different, although very 
similar physical features mark the strata, as though thejr had 
been subjected to the same or very similar physical conditions. 
1 
Before we get quite to the middle of town seven, the rdck, clay 
and even the soil, in many places, begin to wear an ochrey ap¬ 
pearance, which continues more or less for a distance of three 
or four miles. 
When this first attracted my attention I treated it lightly, 
supposing it to be the outcropping of the north and south 
ranges of fissures in their northern extension, and regard¬ 
ed it more as an evidence of a north and south axis than any¬ 
thing else. But noticing it in several places to the east and 
west of where I first discovered it, I began'to entertain hopes that 
these ochrey out-croppings were indications of another east and 
west belt, similar to those in the lead district. With this impres¬ 
sion I commenced a systematic investigation of the surface indi¬ 
cations both to the east and the west. But along a region of 
