EFFECTS REFERRED TO THEIR CAUSES. 759 



2. Through the unequal wear of harder and softer grains, under the action of the 

 waves or running water, the softer being worn first and drifted off, and so leaving the 

 harder behind, as in the making of a sand-beach, p. 670. 



3. By the action of the winds. 



4. Transportation of Fragmental Material. — l. By fresh or salt water, 

 pp. 647, 666. 



2. By ordinary floating ice, icebergs, or glaciers, pp. 538, 683, 686. 



3. By the winds, pp. 631, 632. 



4. By means of migrating animals, p. 607. 



5. By the help of floating logs or living plants, p. 607. 



5. Deposition and Arrangement in Beds of Fragmental Material. 

 — 1. By winds, p. 631. 



2. By fresh waters in their ordinary condition, or during occasional or annual floods, 

 pp. 650, 651. 



3. By fresh waters in a prolonged flood, producing till, p. 546. 



4. By a plunging flow of waters, pp. 546, 671. 



5. By marine waters, p. 668. 



6. By glaciers or icebergs, p. 666, 684. 



6. Organic Contributions to Fragmental and other Deposits. — 

 1. Of a Calcareous nature, pp. 59, 60, 135, 615. 



2. Of a Siliceous nature, pp. 59, 60, 135. 



3. Of Excrementitious origin, or phosphatic, pp. 59, 60, 613. 



4. Of Carbonaceous character, pp. 60, 61, 612, 616. 



7. Colors of Fragmental Deposits, Limestone included. — l. Brown- 

 ish-yellow to broivn colors due to limonite, the hydrous oxyd ofiro% Fe 2 3 -f- l^HO. (1.) 

 The limonite derived directly from the oxydation attending the disintegration by which 

 the sands were made, the sands having not been subjected afterward to washing on a 

 seashore, which removes such iron-oxyd. 



(2.) The limonite that which is deposited in a low wet region, where the fragmental 

 deposit was in process of accumulation ; not a possible result in an open estuary or on an 

 open coast, p. 694. 



(3.) The limonite produced by the action of ordinary waters on a deposit, pervious to 

 water, containing an iron-bearing mineral, p. 694. 



2. Brownish-yellow or brown color, due to the hydrous iron-silicate, palagonite. This 

 mineral is formed when a bed of volcanic cinders or granulated volcanic rock is sub- 

 jected to the action of warm waters, the pyroxene of the material being altered, by 

 losing part of its silica, having its iron changed to the sesquioxyd state, and taking in 

 water. 



■3. Green, Brownish-green, or Olive-green color, due to the hydrous iron-silicate, glau- 

 conite. — The silica in glauconite, the green mineral giving the color to the green-sand 

 of the Cretaceous and other formations, is supposed to come from the siliceous secretions 

 of minute Sponges in the cellules of Rhizopods, etc. ; but the process of formation is 

 not understood. 



4. Bed color, due to red oxyd of iron, Fe 2 3 . — (1) From the heating of beds con- 

 taining limonite as the coloring material, limonite becoming the red oxyd when heated, 

 p. 750. 



(2.) From the oxydation of the iron of an iron-bearing mineral through the action of 

 moisture and heat, p. 695. 



(3.) The same as (2), at the ordinary temperature in dry warm regions. 



5. Black and Brownish-black colors. — (1.) From the presence of carbonaceous sub- 

 stances, derived from vegetable or animal matters; in which case the rock will burn 

 white. 



(2.) From the presence of an oxyd of iron; in which case the rock will burn red. 

 (3.) From the presence of an oxyd of manganese; in which case the rock will remain 

 black or bluish-black, on heating. 



