396 TRANSACTIONS OF THE 



series becomes gradually thinner northward, and was not 

 observed much farther up than Cross street. The great 

 thickness and weight of clay and sand resting upon this 

 lower black mud have compacted it very closely, and 

 made it in many places an indurated, although wet clay. 

 Here and there in softer patches rest the embrowned 

 leaves of various recent trees and shrubs, such as the 

 Swamp Maple, the common Beach, the Scarlet Oak, the 

 Chestnut, Alder, Willow, and the needles and round fruit 

 of the Cypress. These latter were very little flattened 

 out, but neither they nor any of the leaves were fossilized. 

 They were saturated with water, were quite flexible, and 

 were found almost exclusively in wet pockets or cracks of 

 the black clay, sealed up sometimes with twigs and bits of 

 bark. The section at this place has at base a stratum of 

 black clay 5 feet, or more, in thickness, most of which 

 overlies the roots of the Cypress tree stumps which stand 

 erect and in undisturbed position there. One of these 

 stumps was 7 feet in diameter and 6 feet high, others 

 (fifteen were counted and roots of others seen) were about 

 three feet or less in diameter, but not so high, with ragged 

 upper ends, and more or less of the bark remaining. This 

 stratum is quite damp throughout, flaky in large part, and 

 decidedly wet in spots where pockets and cracks occur. 

 Above this rests a drier stratum of lead-colored, dense 

 clay, 6 feet in thickness, separated by a perfectly defined 

 line from the underlying bed. This is followed above by 

 about 5 feet of yellowish or pale clays, parted into three 

 strata by a few inches of pale sand. These clays becom.e 

 more sandy above, and are separated at base by a well- 

 defined line, but conform to the mostly level surface upon 

 which this member rests. This third bed is almost dry 

 throughout and is separated from the overlying, in part 

 cross-bedded, sand by a distinct structural unconformity. 

 The strata of the McHenry Formation are designated by 



