Maryland Geological Survey 409 



but its top is reached near ilic summit of Four Mile Eidge on tlie road to 

 Lonacouiiig. The horizontal distance, measured on the map, across the 

 Savage Eiver is but 1 mile between the top and bottom of the Catskill 

 formation which on averaging the dip, would give a thickness of about 

 1700 feet for the formation. It is probable, however, that the horizontal 

 distance is underestimated. The red shales and sandstones of the Catskill 

 formation are also well shown to the southwest of the above locality on the 

 road from Savage River up Warnick Eun nearly to the top of Elbow 

 Mountain. 



At the western end of the Baltimore and Ohio Railroad cut just east 

 of Altamont station are red shales and sandstones. A little farther east 

 are greenish, coarse grained sandstones and shales in which a few im- 

 perfectly preserved pelecypods were found. The dip is between 16° 

 and 17° S. E. This cut as shown on the Geological Map of the Piedmont 

 Folio is near the top of the Catskill and it is apparently the zone 

 of greenish rocks in the upper part of tliat formation. The occurrence 

 here of a few very imperfectly preserved fossils becomes important. The 

 lithological character of the rocks in the upper part of the Catskill 

 shows that there was a somewhat gradual change from the conditions 

 under which they were deposited to those of the Pocono. 



The greater part of the Catskill is simply an. alternation of red 

 shales and sandstones with zones of greenish rock in the lower and upper 

 part of the reds. The Chemung fauna survived for some time after the 

 conditions were such that thick masses of brownish-red to red rocks were 

 being deposited, but most of the fossils are found in zones of rock which 

 in lithological characters more closely resemble those of the ordinary 

 Chemung than the Catskill. It is possible that other localities of the 

 greenish rocks in the upper Catskill will furnish fossils and these will 

 probably be confined to those forms capable of life under very adverse 

 conditions as for example the comparatively few species of pelecypods 

 and fishes which Irave been found in the Oneonta and Catskill formations 

 of New York and Pennsylvania. 



