登陆注册
5193100000052

第52章 ON THE FORMATIONS OF THE PAMPAS(1)

Mineralogical constitution.

Microscopical structure.

Buenos Ayres, shells embedded in tosca-rock.

Buenos Ayres to the Colorado.

San Ventana.

Bahia Blanca; M.Hermoso, bones and infusoria of; P.Alta, shells, bones, and infusoria of; co-existence of the recent shells and extinct mammifers.

Buenos Ayres to Santa Fe.

Skeletons of Mastodon.

Infusoria.

Inferior marine tertiary strata, their age.

Horse's tooth.

BANDA ORIENTAL.

Superficial Pampean formation.

Inferior tertiary strata, variation of, connected with volcanic action;Macrauchenia Patachonica at San Julian in Patagonia, age of, subsequent to living mollusca and to the erratic block period.

SUMMARY.

Area of Pampean formation.

Theories of origin.

Source of sediment.

Estuary origin.

Contemporaneous with existing mollusca.

Relations to underlying tertiary strata.

Ancient deposit of estuary origin.

Elevation and successive deposition of the Pampean formation.

Number and state of the remains of mammifers; their habitation, food, extinction, and range.

Conclusion.

Localities in Pampas at which mammiferous remains have been found.

The Pampean formation is highly interesting from its vast extent, its disputed origin, and from the number of extinct gigantic mammifers embedded in it.It has upon the whole a very uniform character: consisting of a more or less dull reddish, slightly indurated, argillaceous earth or mud, often, but not always, including in horizontal lines concretions of marl, and frequently passing into a compact marly rock.The mud, wherever I examined it, even close to the concretions, did not contain any carbonate of lime.

The concretions are generally nodular, sometimes rough externally, sometimes stalactiformed; they are of a compact structure, but often penetrated (as well as the mud) by hair-like serpentine cavities, and occasionally with irregular fissures in their centres, lined with minute crystals of carbonate of lime; they are of white, brown, or pale pinkish tints, often marked by black dendritic manganese or iron; they are either darker or lighter tinted than the surrounding mass; they contain much carbonate of lime, but exhale a strong aluminous odour, and leave, when dissolved in acids, a large but varying residue, of which the greater part consists of sand.These concretions often unite into irregular strata; and over very large tracts of country, the entire mass consists of a hard, but generally cavernous marly rock: some of the varieties might be called calcareous tuffs.

Dr.Carpenter has kindly examined under the microscope, sliced and polished specimens of these concretions, and of the solid marl-rock, collected in various places between the Colorado and Santa Fe Bajada.In the greater number, Dr.Carpenter finds that the whole substance presents a tolerably uniform amorphous character, but with traces of incipient crystalline metamorphosis; in other specimens he finds microscopically minute rounded concretions of an amorphous substance (resembling in size those in oolitic rocks, but not having a concentric structure), united by a cement which is often crystalline.In some, Dr.Carpenter can perceive distinct traces of shells, corals, Polythalamia, and rarely of spongoid bodies.For the sake of comparison, I sent Dr.Carpenter specimens of the calcareous rock, formed chiefly of fragments of recent shells, from Coquimbo in Chile: in one of these specimens, Dr.Carpenter finds, besides the larger fragments, microscopical particles of shells, and a varying quantity of opaque amorphous matter; in another specimen from the same bed, he finds the whole composed of the amorphous matter, with layers showing indications of an incipient crystalline metamorphosis: hence these latter specimens, both in external appearance and in microscopical structure, closely resemble those of the Pampas.Dr.Carpenter informs me that it is well known that chemical precipitation throws down carbonate of lime in the opaque amorphous state;and he is inclined to believe that the long-continued attrition of a calcareous body in a state of crystalline or semi-crystalline aggregation (as, for instance, in the ordinary shells of Mollusca, which, when sliced, are transparent) may yield the same result.From the intimate relations between all the Coquimbo specimens, I can hardly doubt that the amorphous carbonate of lime in them has resulted from the attrition and decay of the larger fragments of shell: whether the amorphous matter in the marly rocks of the Pampas has likewise thus originated, it would be hazardous to conjecture.

For convenience' sake, I will call the marly rock by the name given to it by the inhabitants, namely, Tosca-rock; and the reddish argillaceous earth, Pampean mud.This latter substance, I may mention, has been examined for me by Professor Ehrenberg, and the result of his examination will be given under the proper localities.

I will commence my descriptions at a central spot, namely, at Buenos Ayres, and thence proceed first southward to the extreme limit of the deposit, and afterwards northward.The plain on which Buenos Ayres stands is from thirty to forty feet in height.The Pampean mud is here of a rather pale colour, and includes small nearly white nodules, and other irregular strata of an unusually arenaceous variety of tosca-rock.In a well at the depth of seventy feet, according to Ignatio Nunez, much tosca-rock was met with, and at several points, at one hundred feet deep, beds of sand have been found.

I have already given a list of the recent marine and estuary shells found in many parts on the surface near Buenos Ayres, as far as three or four leagues from the Plata.Specimens from near Ensenada, given me by Sir W.

同类推荐
  • 同治甲戌日兵侵台始末

    同治甲戌日兵侵台始末

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • LAWS

    LAWS

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 廿一史弹词

    廿一史弹词

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 算山

    算山

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 玉耶经

    玉耶经

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
热门推荐
  • 黑星降临

    黑星降临

    在不断的轮回中,没有永存的事物。星变事件导致了地球以及整个宇宙星系的毁灭,幸运的是部分精英人类因为乘坐方舟穿越得以幸存下来,而在他们回来后宇宙已经变得面目全非,但是王者大陆成为了人类文明繁衍的新的起点......
  • 牛顿:人类理性主义的旗帜

    牛顿:人类理性主义的旗帜

    《图说世界名人:牛顿(人类理性主义的旗帜)》介绍了,艾萨克·牛顿,人类历史上出现过的最伟大、最有影响的科学家,同时也是物理学家、数学家和哲学家,晚年醉心于炼金术和神学。他在1687年7月5日发表的不朽著作《自然哲学的数学原理》里用数学方法阐明了宇宙中最基本的法则——万有引力定律和三大运动定律。这四条定律构成了一个统一的体系,被认为是“人类智慧史上最伟大的一个成就”,由此奠定了之后三个世纪物理界的科学观点,并成为现代工程学的基础。牛顿为人类建立起“理性主义”的旗帜,开启了工业革命的大门。
  • 穿越秦朝之祖龙的管事

    穿越秦朝之祖龙的管事

    嫪隘,一名与大秦始皇母亲身边宦官名字相像的学生,因为一场梦境开启了一场历史的征程。嫪毐之乱,车裂极刑能否重新改写。
  • 数星星的夜

    数星星的夜

    陆星辰,他身边的标签总是少不了高恩星的存在。高恩星是陆星辰心中坚定的初恋。从八岁到十八岁,他的身影一直都在高恩星身边打转。他将高恩星视作命定的恋人。友情坚定的他们,在碰到爱情的字眼开始断裂。两人的距离越来越远。正当高恩星想要尝试与陆星辰交往时,意外在下雨天碰见了那个令她一见钟情难忘的男生,边唯枫。高恩星与边唯枫一见钟情,再见倾心。两人机缘巧合下遇见过三次。似乎是命定的相遇。两人很快熟识成为了知心、坦诚相见的朋友。两人之间暧昧的情愫也渐渐展开。可是一切都没有高恩星想象的那么简单。如果一个人有着内心敏感的软肋,那陆星辰的软肋是高恩星,可边唯枫的软肋却是一个叫作唐果的女生。只要唐果呼唤边唯枫,边唯枫必须尽快赶到她的身边。唐果的突然出现,信誓旦旦的拿着证据向高恩星宣誓着主权,而边唯枫也因误会了高恩星与陆星辰的感情关系,两人产生隔阂,误会深深。从朋友再次变回了陌生人。陆星辰选择守护在高恩星身边,一次又一次的劝解,他终于释怀,决定放手。一年后初入大学,高恩星成为了边唯枫的同校师妹。两人在再一次产生交集。误会终究解释,两人冰释前嫌走在了一起,因为高恩星的选择和考虑,开始了漫长的地下恋情。两年后,两人矛盾重重,总是为对方考虑太多,最后二人因为毕业去留问题画上了句点。四年后,两人再次重逢。庆幸的是,他们从未忘记过对方。只是一切,不再是从前了。高恩星:“你想要我都给你,包括离开你。”陆星辰:“我真没喜欢过你,只是直接爱了。”边唯枫:“世界像巨大水晶球,我隔着玻璃,只想得到你。”
  • 我是一只女鬼

    我是一只女鬼

    一朝醒来,却与世间天人永隔!一边躲避着地府阴差,一边以鬼之形看尽万生百态。我是孟绯,一个已经死了却不愿投胎的女鬼。我用我的双眼记录了那些精彩无比却又冷漠无情的故事;我用我的经历告诉你们,这世间最恐怖的莫过于一颗充满原罪的心!我行走在这世间,杀过人,爱过人,也恨过人。我失去了最开始的善良和纯真。请跟随我的足迹,与我一同见证这个世界的故事!我叫孟绯,是一只女鬼。
  • 重生之拐个忠犬夫君

    重生之拐个忠犬夫君

    上辈子,他亲眼送她嫁予他人,数载不复相见;再见时,她已被折磨的不复人形,他亲手揽她入怀,却听见她泪眼婆娑的诘问:三哥,你是否早已厌弃淼淼?他心如刀绞,却只能眼睁睁见她离他而去;重来一世,她再次出现,他一把将她捉来身边养着,喜怒无常的首辅大人痴缠不休?休想,这辈子,他只能是我沈之叶一人的妻!“三哥,这些人欺负我~”“别怕,爷弄死他丫的!”
  • 六朝文絜

    六朝文絜

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 四家语录

    四家语录

    本书为公版书,为不受著作权法限制的作家、艺术家及其它人士发布的作品,供广大读者阅读交流。汇聚授权电子版权。
  • 鬼坠星夜

    鬼坠星夜

    一千年前黑星落于星河之中,从此天上少了一轮明月。一千年后黑星再度降临,这片天地又会少点什么。这是星的命,还是鬼的命?眼前一直不离的又是谁的影?拨开那层血,我能看见谁?我能碰到谁?我能留住谁?
  • 神捕王妃要出逃

    神捕王妃要出逃

    “淫贼!本小姐以未来捕快身份逮捕你归案!”欺骗老爹是家常便饭,跟娘撒娇有各种手段。虽她家世代书香,但到她这里基本断了。“苏卿家,就你的闺女吧!”身为臣弟事务繁忙,常被逼婚心情不爽。人说他长得俊美貌似断臂,但他金殿之上随手一指……三大五粗,一心想当神捕的千金小姐,一道圣旨被迫嫁给传说中的“阎王”,却至始至终不曾与夫君见过面。某日,她一身夜行衣翻墙回府,他冷冷立于墙头,将她抓住,“你怎么在这?”“我还想问你怎么在这?”老管家顶着满脸的黑线,“王爷,这是您的王妃啊!”“王妃,这是咱们王爷呀!”俗话说不是冤家不聚头,但……聚头了……啊喂,你俩别打了!再某日,她女扮男装翻墙逃出王府,来到江南一小城,偶遇一侠士,与其一道帮弱小,救无辜,结拜成兄弟,喝酒谈天论地,直至某天来到城外,她才知道,原来他竟是……【诙谐+悬疑+江湖+武侠+宫斗+宠爱=绝不弃坑。】