398 The Ohio Naturalist. [Vol. IX, No. 2, 



Georgesville and Harrisburg, and again at the latter place. The 

 rock is all of Devonian age; two rather resistant limestones — 

 Columbus and Delaware — and two much less resistant shales 

 above — the Olentangy and Ohio. 



Along the Olentangy from south to north the terraces may be 

 described as follows. 



West of Lewis Center and across the Olentangy, i. e., on the 

 west side of the river, occurs a terrace about one mile north and 

 south and from 200 to 300 yards wide. Its top stands 30-40 

 feet above the river, descends perceptibly toward the river, and 

 over 20 feet from north to south. The top is quite uneven being 

 rather heavily mantled with gravel, sand and fine alluvium in 

 piles, ridges and bars. Altho the top is so thoroly covei-ed, the 

 terrace front presents solid limestone rock at several points along 

 the river. The stream is undercutting at only one part of the 

 front. In places, the bluffs at rear of the terrace are not sharp, 

 but are old and gently inclined and support continuous cultiva- 

 tion. This condition of the bluff above the terrace is due to the 

 age of the terrace and the considerable dissection to which the 

 bluff has been subjected. Age of the terrace is attested not only 

 by the condition of the bluff behind, but by the height of the 

 terrace above the river. A flood plain occurs near stream level 

 below the terrace most of the length of the front. Relation of 

 this terrace top to rock structure below could not be made out 

 owing to thick alluvial covering; but the same covering gives 

 the terrace a certain cultural value. A church and cemetery, 

 school-house and several good dwellings surrounded by produc- 

 tive farms may be found upon it, while several even larger near- 

 by tracts are much less used. 



One mile east of Hyattsville and across the Olentangy, a 

 small rock terrace about three-eighths of a mile north and south 

 and from a few yards to possibly 200 yards in width, descends 

 gently toward the river with a slope of about 30 feet at widest 

 part and with its edge not more than 20 feet above the water; 

 almost bare rock, but partly covered with a thin sheet of 

 alluvium. Rock is exposed along water's edge nearly the entire 

 length. Terrace consists of the Delaware limestone, but its top 

 is in no measure coincident with structure. A quarry has 

 recently been opened in it. 



Less than half a mile farther up the river on the same side, 

 occurs a fine rock terrace over one and one-fourth miles long and 

 about 300 yards wide at the broadest part, tapering considerably 

 northward. The broad part is over one half mile long. The 

 terrace front rises about 20 feet above the river, and the terrace 

 top rises from the crest toward the bluff only about 20 feet which 

 makes the form a very level-topped terrace. Rock is exposed 

 continuously along the terrace front; and the river parallels it 



