Maryland Geological Survey 163 



description of products 



A. Uxdeb the Hand Lens 

 /. Fine Gravel 

 Some of the 22 grains are quite well rounded, others very angular, but even the 

 angular ones show a glossy surface that suggests solution. They are all deeply stained 

 with yellow ocher. 



II. Coarse Sand 

 The glauconite is abundant in this portion, showing its original botryoidal form, but 

 almost all but the smallest grains appear more or less completely ocherized. The quartz 

 grains are like those in the gravel. Of special significance is a grain half feldspar, 

 half quartz indicating origin from a nearby granitic rock. The proportion of rounded 

 grains is less than in the gravel. 



III. Medium Sand 

 Differs from the preceding in that more of the glauconite is worn. 



IV. Fine Sand 

 Contains some mica but apparently not yet any heavy minerals. 



V. Very Fine Sand 

 A general dark-green appearance with dark limonitic grains. 



VI. Extra Fine Sand 

 The dark-brown limonitic color predominates in this. 



Xellow, limonitic. 



VII. Clay 



B. Under the Miceoscope 

 I. Very Fine Sand 



(1) Light 

 Quartz : feldspar = 75 : 25. 



Though most of the feldspars, like the quartz grains, are stained by ocher, the large 

 proportion of fresh, unweatbered feldspars is striking. 



(2) Heavy 



(a) Attracted at 2000 Ohms 

 Almost all glauconite, so that the identification of other minerals is difficult. The 

 following were recognized: muscovite, epidote, serpentine, staurolite (?). Most of the 

 glauconite is quite opaque, at best only cloudily translucent at the borders. 



(b) Rejected at 2000 Ohms 

 Dominant. — Muscovite, enstatite, zircon. 

 Rarer. — Rutile, garnet, biotite, tourmaline, serpentine, apatite (?). 



//. Extra Fine 

 Many flakes of brown, granular ocher. 



III. Clay 

 The clay appears all granular, the usual fibrous portions which characterize the clay 

 not having been recognized. This probably means that it is mostly secondary limonitic 

 matter, not primary clay. 



Summary and Conclusions. — (1) It is especially to be borne in mind 

 that there is really almost no clay present, the abundant material classi- 

 fied under this head being probably almost all limonite. 



