GEOLOGY. 353 



plants impressed upon them, — and hence they have obtained 

 the name of dendrite stones. The porphyry of Sinai and St. 

 Catherine is distinguished by the same remarkable appear- 

 ances, — a circumstance which has induced some naturalists 

 to call it marmor embuscatum, or b\ishy marble. It was this 

 singular feature that led Buxtorf to derive the name of Sinai 

 from the bushes (the tamarisks and acacias) figured in the 

 rocks ; although it seems more natural that the appellation 

 should have originated from the shrubs themselves, as they 

 are known to abound in these deserts.* Shaw noticed some 

 branches of this fossil tamarisk that were nearly half an inch 

 in diameter ; the constituent matter appeared rather of a 

 mineral substance, not unlike the powder of lead-ore, which 

 crumbled into dust when touched or rubbed with the fingers. 

 The porphyry, he says, is sometimes of so small and compact 

 a grain that the contexture is not inferior to the ophites or ser- 

 pentine marble ; and he thought it probable, that out of this 

 rock were hewn the two tables of the law on which the Ten 

 Commandments were written with the finger of God. 



On the shore towards Akaba rise numerous promontories 

 of black trap and basalt, the bases of which have been 

 scooped by the sea into creeks, resembling small lakes with 

 very narrow entrances. Some of these clifTs, which run close 

 by the water's edge for upwards of a mile, present granite 

 and red porphyry crossing each other horizontally or perpen- 

 dicularly in irregular layers. The granite of this peninsula 

 exhibits the same numberless varieties, and the same beautiful 

 specimens, of red, rose-coloured, and almost purple, that are 

 to be found nearEs Souan and above the cataract of the Nile. 

 The transitions from primitive to secondary rocks, partaking 

 of the nature of greenstone or graywacke, or hornstone and 

 trap, present also an endless diversity, the description of which 

 would only tire the patience of the reader. Om Shomar con- 



* Sinai mentis nomen a sine, rubus, quod lapides inventi in ea 

 figuratum in se habuerint rubum, &c. Buxtorf in voce nJD- 

 Other commentators say that sme also signifies a breast ; and as 

 Mounts Sinai and St. Catherine are the highest peaks in that 

 quarter, they might be so called from their likeness to that part 

 of the human body ; a derivation far less probable than the other. 

 The dendritic appearance of these rocks is mentioned by Pros- 

 pero Alpino (Hist. Nat. Egypt, cap. vi. p. 147), who speaks of 

 the "silices sylviferae, in quibus lapidibus sylvag, herbaruin, 

 fruticum, &c. pictae imagines cemuntur." 



Gg2 



