184 PROCEEDINGS OF 



of land, considerably and re^larly curved to the eastward, and becoming very 

 narrow towards the extremity. It presents the aspect of a low sandy beach ; and 

 yet, almost immediately from its western side, the water suddenly descends to a 

 depth of sixty feet. A few miles north of the point, a rock appears, which I shall 

 presently describe, and which I have no doubt forms the foundation of the penin- 

 sula, as it is manifest that the sand must have some solid basis to enable it to resist 

 the storms of centuries. This rock has originally been a stratum of coarse sand, 

 full of fragments of Balanus proteus, mixed with many whole specimens of the 

 same, and of Pecten Madisonius, which abound on the upper surface. Much of 

 the sand has been washed away, and the remainder of the stratum has become ce- 

 mented by carbonate of lime, and oxide of iron. It is a very porous rock, with an 

 exceedingly craggy or irregular surface, rising to a level of about six feet above the 

 river. Over this rock is a stratum composed of mingled sand and clay, with the 

 same fossils, in a friable state, four feet thick ; then follows a bed of gravel, with 

 an occasional pebble, one foot in thickness; and the highest stratum consists of clay 

 without fossils, seven feet thick. 



Near the mouth of St. Leonard's creek, resting on the fragmentary rock above 

 described, is a stratum of fine siliceous sand, cemented by carbonate of lime, in 

 which arc imbedded innumerable casts of Perna maxillata. With these the Pholas 

 ovalis occurs abundantly, a lithodomus bivalve, always accompanying the Perna in 

 Maryland, the thick shell of which it perforated, and where it may often be ob- 

 tained. This stratum is about twelve feet thick. 



On the western shore of the Patuxent, in St. Mary's county, the fossilliferous 

 strata are visible at the mouth of Cuckold creek, just above the level of the water, 

 and continue in a range of cliffs, northward, to within about twelve miles of Bene- 

 dict. These beds, dipping to the southeast, soon give place to the upper tertiary, 

 below the creek, whilst up the river they gradually rise to an elevation of at least 

 fifty feet, in places, above the tide. At the landing of Dr. Gilliams, a few miles 

 north of the last named locality, a rock first makes its appearance, nearly on a level 

 with the river, which is very similar in aspect to that on the opposite shore ; but in 

 place of Balani, the fragments of which it is chiefly composed, are those of a largo 

 Scutclla, which I have named S. Aberti. Many perfect specimens have been origi- 

 nally imbedded among these small fragments ; but owing to their perishable nature, 

 and the incessant action of the waves of the Patuxent upon the loosely cemented, 

 very porous rock, few can be obtained nearly entire. The fragments of Scutella 

 are much in the same state, and appear to have been subjected to attrition in a 

 manner precisely similar to those of the recent shells of Anastatia Island, on the 

 coast of Florida, which constitute a mass sufficiently coherent to be used as a build- 

 ing material in St. Augustine. This Scutella rock is very clearly a member of the 

 medial tertiary formation, being identified by casts of characteristic shells, 'and 

 especially by the large Pecten Madisonius, which abounds in single valves. We 

 traced this interesting stratum a distance of six miles north of Dr. Gilliams' land- 

 ing. Here it rises to a much greater elevation, and beneath it another stratum of 

 the same formation, full of casts of Perna maxillata, extends to the level of the 

 river. This locality is near the landing of Chapman Billingsly, Esq., who received 

 us with cordial hospitality, and politely assisted us in exploring the vicinity. Above 

 the Scutella rock a thin bed of Ostreavirginiana occurs in sand. Two or three 



^1 



