rock, which If nearly buried in the soil, were eiposed to mcleorte action, a deep groove 

 woold soon be formed in Ihe line were the laminae port and licnd inward*. 



The metallic vein formerly noticed runs NE. by TL. The whole rack is tiitwe tc d by olhar 

 planes in ihe same direction, as appear* from slight searings on the surface. Another princi* 

 pal divisional plane it 5E, by S, as is well wen by the direction of the cd^cs of Mjmi: Urge 

 rock* anjoinmjj. 



To (he MY, nf the p;ronvcd reck first described, the rocks on the beach are either extended 

 and fiat, and a few fret above (be level of ihc beaeh^pr > were worn down, nearly la the 

 level of I he beach > they arc broken in. (a sin all cnboidal and spherical fragments deposed, 

 where this has been recently dene^ in regular lines, It is obviout how reftdtlf rocks with 

 such at structure may be worn into cavities and channels. 



II iviii;- now initial rrntly - utm <trl:uU for tin? srope i>T this ppiT. il n : m :i i 1 1 r to eiplain 

 the conclusions to which I have been led by my observations. En 1mlh , however, I have 

 not much la say an this subject (save what U of a general speculative nature) that has 

 mot been anticipated in the second portion of the proceeding remark a. The Grit circum- 

 stance worthy of note is, that the observer after he has partially ciplorcd ike bland is 

 wholly unable to conjecture j at many of the Points K whether the ncil few paces; aton^ 

 the shore wiJt l>riii|j hi in la a gnmilie, a sycnitJc, a diorilic a h n ilcir rro-L , m i-vtu 

 whether the mass before bim f although ol the place where In? has broken off a fragment 

 decidedly a granite , may not in other places bo found to consist of why or all of these 

 other minerals. The Island , in its general mineralogy , seems to break through all arbi- 

 trary distinctions of pin Ion tc and volcanic f -and to confirm r in a very strtkiiirj manner, 

 the coneluHLcin , to which mud r^rdo-jTL*!* bate arrived f that these (Treat clas+e* of rocks are 

 essentially similar in origin. The dilterence in structure, as between a compact basalt and 

 a crystalline pnmltc > is referred lo the difference in pressure to which the basalt, cooling 

 near the surface , and the granite $ cooling at [great depths f were subject at the time of 

 their solidification* That this may , or rather most have a fjreat influence, is certain; bat 

 tbe occurrence of such rocks as these of i'ulo Ubin cannot be etplaincd by difference oT 

 pressure p uud , indeed, proves thai there are in nature CAQUa independent of variations in 

 pressure t adequate to the con lcuiparancou.il production of rocks bi4oiijjio;f both to the volca- 

 nic arul the plulonic series (1), Under whatever circumstances the granite of the Island 

 wae produced, under the same circumstances were the syenites and n;rccnalones also produced; 

 and same other cause than i;n.-at d lITl- fence of dcplli and con*cu;ucnt pressure must have 

 dctcrmini-il tin' mutations in Ibis mineral character of the mass. But if it be certain, that 

 such cause existed t would not that cause of itself be adequate at a general origin of the 

 difference* in igneous rocks attributed to inequalities of pressure ? Mr. Ltsil (pcrhrip* ihc mngt 

 dislimjuiihcd of our EajjUhLi writers oft ijtolojjy f whether we consider the originality of his 

 vieWH the philosophical spirit in wlikii lln'y an 1 |[cnurally conceived, or the graceful fiini- 



(1) Mi LfE.ii. eminra" lbs lorro. pWUnie la gmniiti (JtUmmt* Vol. I. j* Ij -in! tel. It. Chip, 32.) mhI [ fatri 

 m h id lb* uot icai*- Olhrr writtn. sail pcrhnjn Sir, Lull biuueEf accqiiaailtj . girt it s. *idcr inesiiiny. 



