48 yan. 6, 
Uhler. ] 
lies near the bottom of the alluvial column on the Archean rocks of 
Maryland. 
This Baltimorean formation may be recognized in the prominent hills 
and ridges of variegated red and white, and lead-colored clays which | 
meet the eye near the roads leading along the inner limits of tide-water, | 
between the head of Chesapeake bay, in Cecil county, and the Potomac 
river, in Washington. 
In turning now to the Baltimorean formation, which is especially well- 
developed within the limits of that city, we see rather abrupt hills, rising 
eighty to one hundred feet above the adjacent level, composed chiefly of 
compact clays, alternating with beds of sand, some of which embrace 
slender drifts of quartz pebbles and fragments of kaolinic clay. 
The formation is made up of numerous strata, constituting altogether a 
column of alluvial matter more than five hundred feet deep. That part i 
which-we can examine at or near the level of the lower streets in south 
Baltimore exhibits a dark lead-colored compact clay, well-stratified, and 
resting immediately upon a layer of dense iron clay-stone of only a few 
inches in thickness. Often the clay which comes in direct contact with 
this stone is stained a bright red color, is of a very fine texture, and is 
known as ‘‘puddling-clay.’? On this the distinctly stratified layers of 
dark clay, ranging usually from seven to nine feet in thickness, are built, . 
and consist of strata varying from three inches to fully two feet in thick- | 
ness. Between the finely ground layers, in contact with the smoothest 
surfaces, we meet with the remains of trees, shrubs, vines, ferns, equisete, 
and, perhaps, alge. These fossil remains occur in the greatest profusion, 
accompanied by finely reduced lignite in the upper strata. At least five 
such intervening plant-beds are present in the base of Federal hill and its 
extension eastwards, in each of which some peculiar form of fern, vine, 
or leaf serves to distinguish it from the others. It has been my good 
fortune to discover these beds in this region, and to secure ample collec- 
tions of all the remains at present found in them, and these are now being 
figured and described by Prof. Fontaine, of Virginia. 
From the lowest layer I have taken out plants only of a low type of 
structure resembling alge and nitellas; from the next layer above, equi- 
getee and ferns with strange vine-like structures ; from the layer a few feet 
higher, buds and twigs of trees allied to the cypress and redwoods of Cali- 
fornia, as also leaves of ferns having the form of those of the Ginko ; 
from the fourth layer other ferns, coniferous stems, buds and scales, with 
some leaves of dicotyledons resembling sassafras; and from the upper 
layer leaves which resemble those of the hawthorn, magnolia, willow, and 
hemlock. The less distinctly stratified clay overlying these is rich in | 
lignite, often containing the trunks and limbs of nearly entire trees, some of i 
which have been found with spruce-like cones and needle-shaped leaves. / 
The continuation of this bed upwards is composed of the iron-ore clays 
which form such conspicuous hills and ridges along the road leading to : 
Washington. In this member of the series lie the extensive layers of 
