6 
BULLETIN OF THE LABORATORIES 
era, as claimed by some, or gradually reached its present condition by 
progressive development and continuous differentiation, is most likely 
to be settled by such detailed study of superposed strata. The work 
represented by the notes here given has been the recreation of spare 
moments during less than a year, ’but has been sufficient to indicate an 
almost exhaustless mine of interesting information. It is hoped that 
the study may be pursued much further. The accumulation of mate- 
rial has been greatly facilitated by the co-operation of the class in lith- 
ology of 1886, some members of which have continued to assist in the 
necessary collecting and field-work. Mr. Foerste, of ’87, has also ren- 
dered efficient aid in collecting and otherwise. 
In as much as the study was carried on independently of the pub- 
lished reports it is gratifying to observe the substantial accord of our 
results with those of the Geological Survey, so far as the latter ex- 
tend. The examination was restricted to a band some miles in width, 
extending from Alexandria to Brownsville, with the view of perfecting 
a geological section across the line of contact between the coal meas- 
ures and the sub-carboniferous formations, which alone are here repre- 
sented. Our plan has been to study the various quarries and natural 
exposures, gathering such information as may be furnished by fossils 
or stratigraphy, then proceeding to parallelize as far as possible the 
strata which are recognizable. It is surprising how many hints a bar- 
ren looking heap of rock may often furnish. The dip of strata is often 
only obtainable by the use of a transit as it varies little from -the hori- 
zontal. As we pass from horizon to horizon the imagination sees broad 
sandy shoals, marked by ripples, and here and there exposing to view 
bivalves of unfamiliar form, or detached valves of brachiopods. Again 
a shallow lagoon, with a muddy bottom supporting a luxuriant vegeta- 
tion of Spirophyton sea-weeds, whose broad leaves floated about like 
the pond-weeds of to-day. Among these darted the trilobites, spring- 
ing backward by a quick stroke of the tail, or lazily floating near the 
surface, or crawling along the under surfaces of their leafy retreats. 
In clearer spots the sea-lily spread its graceful but direful petals while 
an occasional horny shielded flsh flashed by in pursuit of slow-swim- 
ming gasteropods. Here one reads proof of a stormy promontory, 
where the waves ravened pitilessly about the abutting cliffs, and scat- 
tered the eroded material in bars and banks within sheltering coves, or 
distributed it by currents more equally over a wide area. Such was 
the condition of Granville and the adjacent townships before it was 
