Only exceptionally, grains larger than 2–3 mm are involved in dune-forming processes. In 16 Late Glacial – Early Holocene inland dunes deposits from three regions of the northern and central Poland, beds, layers, laminae and lenses containing extra-large grains, up to 20.5 × 12.5 × 11 mm in the longest axes, are present. Occurrences of the extra-large grains are documented in the dunes dispersed in three distinct physiographic regions, Biebrza Basin, Central Poland Lowlands, Przedbórz Upland and the adjacent part of the Włoszczowa - Nida Basin. An aeolian genesis of these deposits is proven by sedimentary features and morphology of the landforms, including simple forms of parabolic, longitudinal and transverse dunes, as well as large, complex depositional forms. The extra-large grains occur at various depths in the sandpit sections, ranging from a few tens of centimetres just the above contact of dune deposits with the substrate up to a few tens of centimetres below the top of the dune section. Outcrops with the extra-large grains are located on both lee and stoss sides in the dune landforms. Deposits bearing extra-large grains show nearly horizontal and low angle lamination, which is typical of the dune stoss sides, to high angle foresets, which are typical of lee sides of dune landforms. Several sites display up to seven layers of the extra-large grains, indicating a few episodes of extremely strong and relatively steady wind during the dune-forming period. Estimation of the wind velocity threshold for such coarse material shows values between 23 and 82 m s⁻¹, for speeds 1 m above the surface. On the basis of measured dimensions and volumes of particular pebbles, a principal component analysis demonstrates that the distribution of grain dimensions is clearly heterogeneous between the three physiographic regions of northern and central Poland. The concentration of values from the Central Poland Lowlands dataset is significantly higher than in the other two regions. This might have been caused by the lack of wind-flow terrain constraints in the mostly flat area of the Central Poland Lowlands. In contrast, the relatively high variance of grain dimension parameters could have been caused by the inconstancy of wind velocity and direction over the undulated morphology of the other two regions. The prevailing western direction of transportation points to frontal, episodically hurricane-speed winds (>20–40 m s⁻¹), which were able to transport the extra-large grains during Late Glacial – Early Holocene times, in the area south of the Scandinavian ice sheet. The relatively rare occurrence of layers and laminae with extra-large grains in the investigated dune deposits suggests specific processes leading to their formation. However, reports of 16 outcrops with the extra-large grains imply that aeolian transport of very coarse material is not only a scientific curiosity, but a process occurring on a broader scale.

唯一例外的是，大于2-3毫米的晶粒会参与沙丘形成过程。在波兰北部和中部三个地区的16个冰川晚期–全新世早期内陆沙丘中，存在着床，层，薄片和透镜，这些透镜中最长轴的直径最大为20.5×12.5×11 mm。沙丘分布在三个不同的自然地理区域（比伯扎盆地，波兰中部低地，Przedbórz高地和Włoszczowa的相邻部分-奈达盆地）中的沙丘中记录到了超大晶粒的发生。这些沉积物的风成因已通过地貌的沉积特征和形态证明，包括抛物线形，纵向和横向沙丘的简单形式，以及大而复杂的沉积形式。超大晶粒出现在沙坑段的不同深度，从沙丘沉积物与基底的上述接触的几十厘米到沙丘段顶部以下几十厘米的范围。沙丘地貌的背风面和下垂面都具有大颗粒的露头。带有超大晶粒的沉积物表现出接近水平和低角度的叠层，这是沙丘地表物侧面的典型特征，而到高角度的前兆则是沙丘地貌的背风面的特征。几个站点最多显示七层超大颗粒，这表明在沙丘形成期间出现了几阵极强且相对稳定的风。对此类粗材料的风速阈值的估计显示值为23至82 m s 沙丘地貌的背风面和下垂面都具有大粒露头。带有超大晶粒的沉积物表现出接近水平和低角度的叠层，这是沙丘地表物侧面的典型特征，而到高角度的前兆则是沙丘地貌的背风面的特征。几个站点最多显示七层超大颗粒，这表明在沙丘形成期间出现了几阵极强且相对稳定的风。对此类粗材料的风速阈值的估计显示值为23至82 m s 沙丘地貌的背风面和下垂面都具有大粒露头。带有超大晶粒的沉积物表现出接近水平和低角度的叠层，这是沙丘地表物侧面的典型特征，而到高角度的前兆则是沙丘地貌的背风面的特征。几个站点最多显示七层超大颗粒，这表明在沙丘形成期间出现了几阵极强且相对稳定的风。对此类粗材料的风速阈值的估计显示值为23至82 m s 这是沙丘地形的后风的典型特征。几个站点最多显示七层超大颗粒，这表明在沙丘形成期间出现了几阵极强且相对稳定的风。对此类粗材料的风速阈值的估计显示值为23至82 m s 这是沙丘地形的后风的典型特征。几个站点最多显示七层超大颗粒，这表明在沙丘形成期间出现了几阵极强且相对稳定的风。对此类粗材料的风速阈值的估计显示值为23至82 m s^-1，适用于高于地面1 m的速度。根据测量的特定卵石的尺寸和体积，主成分分析表明，在波兰北部和中部的三个自然地理区域之间，晶粒尺寸的分布显然是异质的。来自波兰中部低地数据集的值集中度明显高于其他两个区域。这可能是由于波兰中部低地的大部分平坦地区缺乏气流地形限制所致。相反，晶粒尺寸参数的相对较高的变化可能是由风速和风向对其他两个区域的起伏形态引起的。西方流行的运输方向指向正面的，狂飙的飓风风（>^-1），它们能够在冰川晚期-全新世早期在斯堪的纳维亚冰盖以南的区域内运送超大颗粒。在研究的沙丘沉积物中，具有超大晶粒的层和薄层的出现相对罕见，这表明导致它们形成的特定过程。但是，有16个露头的大粒谷物的报道表明，风沙运输非常粗糙的物质不仅是科学的好奇心，而且是一个更广泛的过程。