MARYLAND GEOLOGICAL SURVEY 115 



these particular beds, but these laminated strata undoubtedly represent 

 a part of the Beekmantown as developed in the Frederick Valley. 



The northernmost exposures of the Frederick Valley limestones occur 

 at LeGore, Maryland, just before these strata disappear under the red 

 beds. Extensive quarrying operations here have exposed a considerable 

 section of closely folded and evidently repeated beds. The clue to the 

 proper sequence is given by several bands of the normally overlying thin- 

 bedded f ossilif erous building rock that are infolded with the more massive 

 Beekmantown limestones. 



At LeGore the building rock is immediately underlaid by about 100 feet 

 of massive dark blue rather pure limestone in beds two to three feet 

 thick, alternating with similar beds of lighter colored strata. Cephalo- 

 pods of Beekmantown affinities are not uncommon on the weathered edges 

 of these strata. These upper fossiliferous beds are separated by about 

 50 feet of massive light blue limestone with quartz grains, from a lower 

 fossiliferous zone. This comprises several hundred feet of strata similar 

 in lithology and fossils to the upper beds. The section then continues 

 for several hundred feet which appear to be a repetition by folding of the 

 strata just described. Many of these massive beds are very homogeneous 

 and marble-like in character. The quarries at Frederick and to the south 

 also afford excellent exposures of the upper beds of the massive lime- 

 stone, but as the strata are little folded here, the exposed thickness is 

 consequently slight. On account of their ready solubility, outcrops of 

 these pure massive limestones appear only in lowland areas. They also 

 leave no surface residual products such as the quartz or shale fragments 

 of the building rock. 



The Frederick Limestone 



This new name is proposed for the strata in the Frederick Valley over- 

 lying the Beekmantown limestone and containing a fauna probably of 

 Chazyan age. The rocks are shown to advantage in numerous quarries 

 and natural outcrops around Frederick. Fossils are of rare occurrence 

 in these outcrops, but they may be found occasionally in the broad, thin 

 slabs of which the stone fences of the valley are built. 



