JV. H. Darton — Magothy Formation of Maryland. 417 



sands with streaks of red and pink clay of the usual Potomac 

 type. A short way west these sands are exceptionally pure and 

 they are quarried for use in the arts but in the western part of 

 the quarries and beyond they are seen to grade into variegated 

 sandy clays and then pure clays of typical Potomac character. 

 There can be no doubt of the Potomac age of these compact 

 sands and clays lying immediately below the Magothy forma- 

 tion in the district. 



North of the Severn River in this region the Magothy gray 

 and buff sands with brown sandstone fragments cap the higher 

 summits over a considerable area and at many points are seen 

 lying on Potomac clays westward and the compact sand and 

 clay member eastward. The northwesternmost Magothy expo- 

 sure is a brown sandstone cap on a very small, shaly elevated 

 knob a mile east by south from Severn station. 



On the south side of the Severn River the banks are lower 

 and present no notable Magothy exposures. In the slopes 

 south ascending westward nearly to Odenton there are fre- 

 quent outcrops in which are seen gray and buff sands with 

 brown sandstone masses. They lie on a gentle undulating 

 plane of unconformity with local irregularities, and dip south- 

 eastward at the usual rate of about thirty feet per mile. 



Odenton Region. — In the hills east of Odenton the Magothy 

 beds attain an elevation of 220 feet and cap the higher lands 

 over an irregular area of considerable extent. They are over- 

 lain by several small outlying areas of weathered Severn beds 

 westward and the northwestern edge of this formation extends 

 along the eastern slopes of the Magothy hills. 



In the southwestern extension of the Magothy formation 

 the light colored sands give place to darker colored and coarser 

 sediments in which brown sandstones, gravels and conglome- 

 rates prevail. The gravels are most conspicuous a mile and a 

 half east of Odenton in the cuts of the Annapolis railroad, 

 and on the adjoining hills. The relation to the Severn sands 

 is plainly exposed in these cuts and at several points in stream 

 and road cuts in their vicinity and southwestward. The gravels 

 are more or less cemented into a loose conglomerate and inter- 

 mixed with sand and brown sandstone. The aggregate thick- 

 ness is variable but it amounts to 23 feet in the railroad cuts. 

 Two and a half miles southeast of here towards Millersville in 

 the cuts for the Drum Point railroad a somewhat greater thick- 

 ness is seen of buff sand, and brown sandstone, in part spar- 

 ingly pebbly. Typical Potomac clays and sands are exposed 

 underlying the Magothy formation at many points in the 

 Odenton region and the usual unconformity is always very 

 distinct. 



