沙丘

Approximately 30,000 years ago, long on stable sand dune plant root, passes through the long time the decency, has formed the limestone, after the plant dies, the sand dune unceasing migration, causes these calcifications the limestone to reveal the surface, has formed the stalagmite which the present sees.

大约在3万年前，长在稳定的沙丘上的植物根部，经过长时间的风化，形成了石灰岩，植物死后，沙丘的不断移动，使这些钙化的石灰岩露出地表，形成了现在所看到的石笋。

An area of 290 hectares throughout the garden, located in a sand dune, this is a "palace on the sand dunes," said.

整个园林占地290公顷，座落在一座沙丘上，故也有&沙丘上的宫殿&之称。

Secondly the relation of seeding time, average sand dune height , s...

适宜的播区立地条件为沙丘平均高度为10m以下，沙丘密度低于75%，播前自然植被覆盖率为12-25%。

From left: blocks of icy debris, warmed by the sun, tumble down cliffs of the northern ice cap; swirling dust devils leave tracks on defrosting dune surfaces in the south; as polar ice recedes, the surface erodes in scalloped ridges; during spring in the north, sand dunes emerge from the blanket of frost; starburst patterns are created as ice warms into gas and expands, creating channels spreading out radially; when the gas breaks through the ice, it creates plumes and material is carried downwind.

从左侧起依次是：冰碎块，由于被太阳加热，从北部冰帽的悬崖上滚落；漩涡状尘暴在南部解冻的沙丘表面留下的轨迹；消退过程中，极冰在地面侵蚀出圆齿状脊；在北部的春季，沙丘钻出&霜毯&；星暴图案是在冰融化成气体并不断扩散时形成的，在此过程中形成的沟槽呈放射状向外伸展；冰从固态变成气态时产生的气羽流顺风飘散。

Another kind of dunes are barchan dunes.

另一种是新月形沙丘类型沙丘。

Parabolic dunes are the opposite of barchan dunes.

抛物型沙丘是新月形沙丘相反。

The width effects of dune are studied and the reason that the barchan dune is formed on the lee slope of dune is given.

但对于背风坡形状的形成，特别是对新月形沙丘，这样一种沙漠、戈壁上最常见的相对稳定的横向沙丘的背风坡新月形落沙坡的形成和保持，无有完整的理论分析，只是简单地认为其坡度不能大于沙子的摩擦角而已。

Patterns in Nature: Sand Strange creatures slithering up from the Empty Quarter desert floor in the Arabian Peninsula are really a network of barchan dunes—sculpted by winds that over time strike the sand from a consistent direction.

位于阿拉伯半岛一种奇怪的不稳定的滑动来自Empty Quarter沙漠是真正的网络的新月形沙丘――造型被风吹的长期打击沙丘来自一致的方向。

Barchan ; windward flank ; wind speed\|up simulation ; dune shape

新月形沙丘；迎风坡；加速模拟；沙丘形态

The results showed the seeds of ephemerals mainly distributes in 0- 5 cm soil and there are few seeds under the 5 cm soil.

结果表明：短命植物种子主要集中分布于地表0～5cm土壤中，5cm以下土壤中极少存在有活力的种子；沙丘间及沙丘不同部位的种子库密度大小不同，密度自坡底随高度增加逐渐减少，坡底、坡中部及坡顶部密度分别为124粒／m^2、91粒／m^2、66粒／m^2。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。