Patent Publication Number: US-10760224-B2

Title: Twisted block

Description:
This application is a continuation of U.S. Ser. No. 15/283,770, filed Oct. 3, 2016, which is a division of U.S. Ser. No. 14/205,760, filed Mar. 12, 2014, which claims the benefit of U.S. Provisional Application Ser. No. 61/790,268, filed Mar. 15, 2013, the contents of each of which are hereby incorporated by reference in entirety herein. 
    
    
     FIELD OF THE INVENTION 
     A field of the invention is landscape edgers for garden borders and other landscape settings. Another field of the invention is repeating elements forming a surface covering, and more specifically relates to stones, bricks, and pavers for forming surface coverings or other structures. 
     BACKGROUND 
     Edgers are known in the art for edging flowerbeds, forming lawn borders, ringing trees and the like. Edgers can include stones or bricks of various configurations, including simple or more complex geometric shapes. Manufactured units typically are laid end to end to form a line, which can be straight, curved, serpentine, or combinations thereof. Edgers can also be used to form circular rings, ovals and other closed patterns. Example edgers are shown in U.S. design patent Nos. RE37,694 and D471,990, both by Thomas Riccobene. 
     Additionally, it is well known to cover surfaces, such as walkways, driveways, patios, floors, work surfaces, walls and other interior or exterior surfaces with stones, bricks, pavers, tiles and other architectural surface covering units. It is further known to construct walls and other structures with stone and bricks. Conventional surface coverings and structures are also constructed of manufactured pavers, bricks, tiles or other units. Manufactured units are typically provided in geometric shapes, such as squares, rectangles and hexagons, or combinations thereof. Surfaces covered with manufactured units typically are laid in repeating patterns. Alternatively, it is known to lay conventional units in random, non-repeating patterns. Some blocks can be used as either a paver or and edger, as shown for example in U.S. Pat. No. 7,637,688 to Thomas Riccobene. 
     Prior art landscape retaining systems and surface coverings have met with varying degrees of success and failure. As always, there is considerable room for improvement. 
     SUMMARY 
     Embodiments of the invention provide, among other things, a twisted block suitable for use in paving, edging or wall applications. The block has a lower portion having parallel, substantially vertical side faces that are spaced apart by a first width. An upper portion of the block has parallel, substantially vertical side faces that are spaced apart by a second width. The second width is smaller than the first width of the lower portion. The upper portion is rotated or twisted relative to the lower portion such that the side faces of the upper portion are angled relative to the side faces of the lower portion. A transition portion between the upper and lower portions has slanted sides extending between one or more sides of the lower portion and one or more sides, respectively, of the upper portion. 
     In a non-limiting example embodiment, the lower portion generally defines a first trapezoid in plan view, and the upper portion generally defines a second trapezoid in plan view. In other example embodiments, the lower portion and upper portion each define squares, rectangles, or other quadrilaterals. Transition portions having slanted sides can be disposed on one or both sides, one or both ends, or any combination of sides and ends. The transition portion can be located at a lower location closer to a bottom surface of the block, or can be located at a higher location. Optional gaps can be provided in the transition portion and the lower portion on one or more sides or ends. Such units can be used to construct a pervious surface covering. 
     A system for edging comprises a plurality of blocks (e.g., two or more, with no upper limit) including at least first and second adjacent blocks. The blocks are abutted end to end in a straight line. The upper portions of the blocks are uniformly slanted relative to the line and are offset relative to each other to form an interesting “saw tooth” or stepped configuration. Another system for edging comprises a plurality of blocks (e.g., two or more, with no upper limit) including at least first and second adjacent blocks. The blocks are abutted end to end so that the blocks are disposed at an oblique angle to one another to thereby form a curved edge. 
     An example surface comprises at least two adjacent bonded rows, each row including at least first and second adjacent blocks. Within each row, the first and second blocks are abutted end to end to form a line. The first and second blocks are uniformly slanted relative to the line and are offset relative to one another. The slants of the first and second blocks in one of the two rows can be substantially parallel. Alternatively, the first and second blocks in one row can be reversed in orientation relative to the first and second blocks in an adjacent row. Other patterns for arrangement of the blocks include, but are not limited to, herringbone, running bond, half bond, basket weave, “I” formations, etc. Surfaces can include combinations of different blocks, including blocks defining respectively different quadrilateral shapes. Such blocks can be disposed along the surface, as an edger, or both. In a particular example embodiment, blocks defining one quadrilateral shape, such as a square, provide a paving surface, while blocks defining another quadrilateral shape, such as a trapezoid or rectangle, border the square blocks and provide an edge. 
     Various embodiments of the invention are described below by way of example only, with reference to the accompanying drawings. The drawings include schematic figures that may not be to scale, which will be fully understood by skilled artisans with reference to the accompanying description. Features may be exaggerated for purposes of illustration. From the preferred embodiments, artisans will recognize additional features and broader aspects of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top plan view of a twisted block suitable for paving, edging, or for wall applications, according to an embodiment of the invention. 
         FIG. 2  is an end view of the block of  FIG. 1 . The opposing end view of the block is similar to  FIG. 2 . 
         FIG. 3  is an elevational view of one side of the block of  FIG. 1 . 
         FIG. 4  is an elevational view of the other side of the block of  FIG. 1 . 
         FIG. 5  is a perspective view of two adjacent blocks according to  FIG. 1 , with a second end of one block flush with a second end of a second block. 
         FIG. 6  is a top plan view of the two adjacent blocks of  FIG. 5 . 
         FIG. 7  is a front elevation view of the two adjacent blocks of  FIG. 5 . 
         FIG. 8  is a perspective view of two adjacent blocks according to  FIG. 1 , with a first end of one block abutting a second end of a second block. 
         FIG. 9  is a top plan view of a surface covering having rows of adjacent blocks in which the upper portion of the blocks in adjacent rows are slanted substantially parallel to one another. 
         FIG. 10  is a top plan view of a surface covering having rows of adjacent blocks in which the upper portions of the blocks in adjacent rows are slanted obliquely to one another. 
         FIG. 11  is a perspective view of two adjacent blocks according to a second embodiment of the invention, with a second end of one block abutting a second end of a second block. 
         FIG. 12  is a top plan view of two adjacent blocks according to the second embodiment of the invention, with a first end of one block abutting a second end of a second block. 
         FIG. 13  is a perspective view of a twisted block according to a third embodiment of the invention, in which a transition portion is disposed at a higher location with respect to a bottom surface of the block. The opposing view of the block is similar to  FIG. 13 . 
         FIG. 14  is a perspective view of a twisted block according to a fourth embodiment of the invention, in which a transition portion and lower portion of the block includes a gap. The opposing view of the block is similar to  FIG. 14 . 
         FIG. 15  is a perspective view of a twisted block according to a fifth embodiment of the invention, in which a transition portion includes a slanted side on ends of the block. The opposing view of the block is similar to  FIG. 15 . 
         FIG. 16  is a top plan view of a pair of adjacent twisted blocks according to the fifth embodiment, with a second end of one block abutting a second end of a second block. 
         FIG. 17  is a top plan view of a partial surface covering, including a twisted square block according to a sixth embodiment of the invention, edged by a twisted block according to the first embodiment. 
         FIG. 18  is a perspective view of a partial surface covering including two square twisted blocks according to the sixth embodiment edged by a pair of twisted blocks according to the first embodiment. 
         FIG. 19  is a top plan view of a surface covering according to the sixth embodiment of the invention, including a two-dimensional pattern of square twisted blocks according to the sixth embodiment edged by a border of twisted blocks according to the first embodiment. 
         FIG. 20  is a top plan view of a surface covering according to a seventh embodiment of the invention, including a herringbone pattern of rectangular twisted blocks edged by a line of twisted blocks according to the first embodiment. 
         FIG. 21  is a top plan view of a partial surface covering according to an eighth embodiment of the invention, including square twisted blocks having a raised transition portion, and further illustrating a textured top surface on one of the blocks. 
         FIG. 22  is a side elevation view of the partial surface covering of  FIG. 21 . 
         FIG. 23  is a perspective view of a square twisted block according to the eighth embodiment, including a textured top surface. 
         FIG. 24  is a side elevation view of an enlarged portion of a corner of the eighth embodiment block. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1-4  show a block  20  according to an embodiment of the invention. The block  20  is suitable for use in paving, edging, or for wall applications. Preferably, but not necessarily, the block  20  is unitary; that is, the block is preferably made in one piece from the same material, though it is also contemplated that the blocks may be made from a combination of materials. Materials can be selected for particular applications. Example materials for the block  20  include concrete, stone (e.g., masonry stone), plastic, and metal. A non-limiting example block length is twelve inches. 
     As best viewed in  FIGS. 2-4 , the outer surface of the block  20  includes a lower portion  22 , which is disposed at the bottom of the block. As used herein, “lower,” “upper,” “top,” “bottom,” and “vertical” will be used with respect to the top-to-bottom orientation shown in  FIGS. 2-4 . The block outer surface also includes an upper portion  24  that is disposed above the lower portion  22 . A transition portion  26  of the outer surface of the block  20  is disposed vertically between the lower portion  22  and the upper portion  24 . The transition portion generally refers to the portion of the outer surface of the block  20  that transitions from the configuration of the lower portion  22  to the configuration of the upper portion  24  (or vice versa). The lower portion  22  and the transition portion  26  in combination can also be considered a foot for the block  20 . It will be appreciated that though these portions  22 ,  24 ,  26  are described separately for purposes of clarity, the block surfaces defining these portions can have discrete or continuous transitions. Also, the height of each portion may vary across the length and/or width of the unit. 
     As best viewed in  FIG. 1 , in a non-limiting example embodiment, the lower portion  22  generally defines, in plan view or horizontal cross-section, a first trapezoid  28  that theoretically is between points  30 ,  32 ,  34 , and  36 . The first trapezoid  28  can be, for instance, an isosceles trapezoid. The first trapezoid  28  is more particularly defined by a substantially vertical first lower side face  38  (best viewed in  FIG. 3 ) that defines a first base, a substantially vertical second lower side face  40  (best viewed in  FIG. 4 ) that defines a second base, a lower first end face  42  (best viewed in  FIG. 2 ) that defines a first leg, and a lower second end face  44  (not directly shown, but similar to face  42  in  FIG. 2 ) that defines a second leg. As shown in  FIG. 1 , the first lower side face  38  and the second lower side face  40  are spaced apart by a first width W 1 . In this example block  20  the “lower portion” generally refers to the portion of the block which in plan view defines the first trapezoid  28 . This lower portion  22  can be of essentially any height. It is also contemplated that the plan view of the lower portion  22  can be a different shape; e.g. a differently shaped quadrilateral, examples of which are provided herein, though other shapes will be apparent to those of ordinary skill in the art. 
     In an example embodiment, and as best viewed in  FIG. 1 , the block  20  has optional beveled edges  46 ,  48 ,  50 ,  52 . The block  20  includes a bottom surface  53 , which may be part of the lower portion  22 , or may be disposed underneath the lower portion  22 . The bottom surface  53  of the block  20  preferably, but not necessarily, has edges matching the first trapezoid  28 . This bottom surface  53  may be, for example, a smooth planar surface, a textured surface, or a different configuration. 
     The upper portion  24  can (but need not in all embodiments) generally define, in plan view or horizontal cross-section, a second trapezoid  54  ( FIG. 1 ) that theoretically is between points  56 ,  58 ,  60 , and  62 . The second trapezoid  54  has a length that preferably is substantially the same as the first trapezoid  28 , but has a smaller width W 2 . Opposing corners of the second trapezoid, at points  56  and  60 , substantially coincide with respective opposing corners of the first trapezoid, at points  30  and  34 . However, opposing corners of the second trapezoid  54 , at points  58  and  62 , are inwardly spaced from the corresponding opposing corners of the first trapezoid, at points  32  and  36 . Accordingly, as best shown in  FIG. 1 , the second trapezoid  54  is rotated or twisted relative to the first trapezoid  28 , as explained further herein below. Blocks in which the shape defined by the upper portion  24  appears rotated or twisted with respect to the shape defined by the lower portion  22  are referred to as twisted blocks herein. 
     The second trapezoid  54  is more particularly defined by a substantially vertical first upper side face  64  (best viewed in  FIG. 3 ) that defines a first base of the trapezoid, a substantially vertical second upper side face  66  (best viewed in  FIG. 4 ) that defines a second base of the trapezoid, an upper first end face  68  (best viewed in  FIG. 2 ) that defines a first leg, and an upper second end face  70  (not shown in  FIG. 2 , but similar to upper first end face  68 ) that defines a second leg. Thus, the distance between the first upper side face  64  and the second side face  66  defines the width W 2 . 
     The block  20  also includes a top surface  72  (best viewed in  FIG. 1 ), which may be part of the upper portion  24 , or may be disposed above the upper portion. The top surface  24  preferably, but not necessarily, has edges defining a trapezoid similar or identical to the second trapezoid  54 , as shown in  FIG. 1 . In the example block  20 , the top surface  72  optionally includes a beveled edge  74 , best viewed in  FIG. 1 , which generally follows the shape of the second trapezoid  54 . In this example block  20  the “upper portion” generally refers to the portion of the block  20  which in plan view defines the second trapezoid  54 . However, in other embodiments the upper portion  24  can have a different shape in plan view, such as a different quadrilateral shape, examples of which are provided herein, and other shapes will be apparent to those of ordinary skill in the art. 
     Theoretical points  56  and  60  of the second trapezoid  54  extend beyond the surface of the upper portion  24  due to the first and second vertically oriented bevels  46 ,  48 . Theoretical points  58  and  62  of the second trapezoid  54  in the example block  20  are disposed at the intersection of the second upper side face  66  and upper first end face  68  (point  58 ), and at the intersection of the first upper side face  64  and upper second end face  70  (point  60 ), respectively. 
     The transition portion  26  includes a first side transition portion  84  (best viewed in  FIG. 3 ) disposed between the first lower side face  38  and the first upper side face  64 , and a second side transition portion  92  (best viewed in 
       FIG. 4 ) disposed between the second lower side face  40  and the second upper side face  66 . The first side transition portion  84  includes a slanted side. This slanted side  84  extends downwardly and outwardly from an inner edge  86  disposed at the first upper side face  64  to an outer edge  88  that is disposed vertically above the outer edge of the first lower face  38 . The inner edge  86  and the outer edge  88  intersect at an acute angle both in plan view as shown in  FIG. 1  and in side elevational view as shown in  FIG. 3 . Slanted side  84  is generally triangular shaped being defined by inner edge  86 , outer edge  88  and a third edge  89  adjacent the end of the block. The outer edge  88  in turn defines a substantially triangular vertical surface  90  that extends vertically from the outer edge  88  to the bottom edge  91  of the first lower side face  38 . Thus, in the example block  20 , the outer edge  88  also defines the first base of the first trapezoid  28  in plan view. 
     Similarly, the second side transition portion  92  ( FIG. 4 ) includes a slanted side that extends from the second upper side face  66 . Particularly, the slanted side  92  extends downwardly and outwardly from an inner edge  94  disposed at the second upper side face  66  to an outer edge  96  disposed vertically above the second lower side face  40 . The inner edge  94  and the outer edge  96  intersect at an acute angle, preferably the same angle as that of the intersection of the inner edge  86  and the outer edge  88 . Slanted side  92  is generally triangular shaped defined by inner edge  94 , outer edges  96  and a third edge  97  adjacent the end of the block. A substantially triangular vertical surface  98  extends vertically from the outer edge  96  to a bottom edge  99  of the second lower side face  40 . Thus, the outer edge  96  in an example embodiment also defines the second base of the first trapezoid  28  in plan view. The inner edges  86  and  94  of the first side and second side transition portions  84 ,  92  are spaced by the second width W 2  shown in  FIG. 1 , and the outer edges  88 ,  96  are spaced by the first width W 1 . 
     Referring to  FIGS. 1-4 , the example block  20  includes a vertically oriented first end  100  and a vertically oriented second end  102 . The vertically oriented first end  100  in this embodiment is shared by (i.e., includes) both the upper first end face  68  and the lower first end face  42 . In this way, the first leg of the first trapezoid  28  and the first leg of the second trapezoid  54  are in the same plane of the vertically oriented first end  100 , as shown in  FIG. 1 . Similarly, the vertically oriented second end  102  is shared by (i.e., includes) both the upper second end face  70  and the lower second end face  44 . Thus, the second leg of the first trapezoid  28  and the second leg of the second trapezoid  54  are both in the same plane of the vertically oriented second end  102 . 
     However, the first upper side face  64  ( FIG. 3 ) and the second upper side face  66  ( FIG. 4 ) are not in the same plane, respectively, as the first lower side face  38  and the second lower side face  40 , due to the twisted configuration of the block  20 . The first and second upper side faces  64 ,  66  are rotated in a horizontal plane by an angle θ ( FIG. 1 ) relative to the first and second lower side faces  38 ,  40 . Angle θ, which can be defined by the first and second slanted sides  84 ,  92 , can be as non-limiting examples between 1 degree and 10 degrees, and is preferably between 2 and 5 degrees. This rotation produces an interesting aesthetic in which the upper portion  24  is rotated or twisted with respect to the lower portion  22 . In the example block  20 , the second trapezoid  54  preferably is substantially contained within and does not substantially extend beyond the area of the first trapezoid  28 . 
     Accordingly, in the first embodiment, the lower portion of the unit is generally trapezoidal in plan view as shown by lines  28  and the upper portion of the unit is also generally trapezoidal in plan view as shown by lines  54 , the upper portion being rotated or twisted relative the lower portion. In other embodiments the lower and upper portions may have other shapes in plan view, including but not limited to squares, rectangles, rhombi, hexagons, octagons, triangles, and other shapes, non-limiting examples of which are shown in the drawings. Further, the shape of the upper portion in plan view need not be the same as the lower portion. Further, the parallel sides of the lower and upper portions need not be linear in plan view, but alternatively can include one or more offsets or other deviations along the length of the unit. The offsets can allow for adjoining or abutting units to interlock with each other. 
       FIGS. 5-7  show an example configuration of two adjacent blocks  110 ,  112  that have essentially the same design as block  20 . Block  112  is flipped relative to block  110 , i.e., the blocks are disposed so that that they are oriented in opposite directions with respect to one another in the horizontal plane (horizontally flipped). Thus, the second end  102  of the block  110  abuts the second end  102  of the block  112 . Additional blocks can be added forming a straight line, every other block flipped, to provide an edge or border. As can be seen in  FIG. 6 , the sides of the lower or base portions  22  (i.e., outer edges  88 ,  96 ) of the adjacent blocks  110 ,  112  are abutted end to end along a line  113 . The sides of the upper portions  24  of the blocks are not in line, however. Instead, the upper sides (the first upper side face  64  and second upper side face  66  of each block  110 ,  112 ) are parallel to each other but offset. Furthermore, the upper portions  24  of the blocks are uniformly slanted or orientated at an angle θ relative to the aforementioned straight line  113  of the edge or border. This creates an interesting aesthetic, which may be described as a saw tooth or stepped configuration. The slanted appearance of the upper portion  24  of the blocks  110 ,  112  combined with the alternating orientation of the upper trapezoid  54  shape provides an interesting pattern, even though the blocks  110 ,  112  (and others in sequence) are in a straight horizontal line. 
       FIG. 8  shows another orientation of two adjacent blocks  114 ,  116 . Blocks  114 ,  116  have essentially the same design as block  20 . A first end  100  of block  114  abuts a second end  102  of block  116 . In this orientation, block  116  is angled (e.g., obliquely angled) relative to block  114 . As additional blocks are added according to this arrangement, the resulting edger or border will curve. As is well known in the art, multiple blocks can assembled in various combinations of same or horizontally flipped orientations to form edges or borders that are straight, curve left, curve right, form rings, curve in serpentine patterns, or combinations thereof. 
       FIG. 9  shows a surface covering  118  having four adjacent rows  120 ,  122 ,  124 ,  126  each having four adjacent blocks  120   a - 120   d,    122   a - 122   d ,  124   a - 124   d,    126   a - 126   d.  Each row of blocks is abutted end to end in a line, such as line  127  for the first row  120 . Within each row adjacent blocks are uniformly slanted relative to the line, as with the blocks  110 ,  112  shown in  FIG. 6 . Further, the slants of the blocks in each row  120 ,  122 ,  124 ,  126  are substantially parallel to slants of the blocks in the other rows. The rows  120 ,  122 ,  124 ,  126  and blocks within each row can be bonded, such as via half-bond (as shown in  FIG. 9 ), quarter-bond, etc., to provide the surface covering  118 . The four rows of four adjacent blocks in  FIG. 9  are merely for illustration, and greater or fewer numbers of rows and/or blocks in each row can be used. Joints between adjacent blocks in rows or between rows can be, but need not be, filled with loose material, e.g., sand, gravel, sod, or with cemented material, e.g., grout or sand with a polymer resin binder. 
       FIG. 10  shows an alternative surface covering  128  having four adjacent rows  130 ,  132 ,  134 ,  136  in half-bond each having four adjacent blocks  130   a - 130   d,    132   a - 132   d,    134   a - 134   d,    136   a - 136   d.  Each row of blocks is abutted end to end in a line, such as line  127  for row  130 , similar to the surface covering  118  in  FIG. 9 . However, in  FIG. 10 , alternate rows  132 ,  136  have blocks that are reversed in orientation from the blocks in rows  130 ,  134 . This causes the slants in blocks in adjacent rows to be oblique to one another. Again, the four rows of four adjacent blocks in  FIG. 10  are merely for illustration, and greater or fewer numbers of rows and/or blocks in each row can be used. In an alternative embodiment (not shown), some adjacent rows are oriented similarly to those in  FIG. 9 , and other adjacent rows are oriented similarly to those in  FIG. 10 . 
     An example top surface  72  is substantially smooth. In some applications, smooth surfaces and/or geometric configurations advantageously provide a modern or contemporary appearance. In other applications, it is desirable to provide a more natural appearance. It is also contemplated that top surfaces (or other surfaces) can be textured for additional aesthetic or other benefits.  FIGS. 11-12  show a pair of adjacent blocks  138 ,  140  that are configured similarly to block  20 , but with a textured top surface  142  in place of the substantially smooth top surface  72 . In  FIG. 11 , the blocks  138 ,  140  are orientated in substantially the same direction as in  FIG. 8 . In  FIG. 12 , the blocks  138 ,  140  are orientated in opposite directions as in  FIGS. 5-7 . Other top surface textures can be optionally provided. In yet further embodiments, the sides and top surfaces can include natural rock features. For the purpose of this application “natural rock features” means false joints, cavities, fissures, planar offsets, shale layers, chips and/or other surface irregularities, edge variations that produce variable width gaps between units, and color variations that singularly or in combination lend a natural rock or stone appearance to the unit. 
       FIG. 13  shows a twisted block  150  according to another embodiment of the invention. On each side of block  150 , the transition portion  152  between lower portion  154  and upper portion  156  is raised with respect to the bottom surface  53 , providing a higher extending lower portion, and forming a more robust base. Put another way, if the lower portion  154  and transition portion  152  are considered a foot, the twisted block  150  can be considered to have a raised foot. The bottom of the transition portion  152  can be disposed above the bottom surface  53  by a dimension of at least one-quarter of the block height. The transition portion  152  includes a generally triangular slanted side  158  that extends downwardly and outwardly between an inner edge  160  at the upper portion  156  to an outer edge  162  disposed vertically above the lower portion  154 . The raised transition portion  152  provides a base for improved paving connection and transfer of shear and load to adjoining paving or edging blocks. The example block  150  can be otherwise configured similarly to block  20  or other twisted blocks. 
       FIG. 14  shows a twisted block  170  according to another embodiment of the invention. Each side of the block  170  includes a transition portion  172  disposed between a lower portion  174  and an upper portion  176 . The transition portion  172  includes a slanted side  178  that extends downwardly and outwardly from an inner edge  180  at the upper portion  176  to an outer edge  182  disposed vertically above the lower portion  174 . A gap  184 , such as a vertical channel or slot, is provided in both the transition portion  172  and the lower portion  174  (i.e., in a foot of the block  170 ), which gap defines two generally opposed faces  186 ,  188 . It will be appreciated that the shape of the gap  184  and the faces  186 ,  188  can vary from the example block  170 . The gap  184  or other such gaps can provide water drainage for a permeable surface covering. It is also contemplated that a transition portion on one side of the block  170  can include the gap  184 , while the other side has a continuous transition portion and lower portion, e.g., similar to transition portion  26  and lower portion  22  for block  20 . In another example embodiment, multiple gaps can be provided in the transitions portions and lower portions (i.e., feet) on one or more sides. The example block  170  can be otherwise configured similarly to block  20 , block  150 , or other twisted blocks. 
     In further embodiments, multiple gaps can be formed in the base portion so as to define spacers between the gaps, similar to the spacers disclosed for example in U.S. Pat. No. 7,393,155, which is hereby incorporated by reference. The spacers of each unit engage adjacent units and maintain the integrity of the layout pattern. 
       FIG. 15  shows a twisted block  190  according to another embodiment of the invention. Each side of the block  190  includes a transition portion  192  having a slanted side  194  that is disposed between a lower portion  196  and an upper portion  198 . The slanted side extends downwardly and outwardly from an inner edge  200  at the bottom of the upper portion  198  to an outer edge  202  disposed vertically above the lower portion  196 . Additionally, at each end of the block  190  the transition portion  192  includes a generally triangular slanted side  204  disposed between a lower portion  196  and an upper portion  198 . This slanted side  204  extends outwardly and downwardly from an inner edge  210  at the upper portion  198  to an outer edge  212  disposed vertically above the lower portion  196 . The inner edge  210  and the outer edge  212  meet at an acute angle. A generally triangular (or generally trapezoidal, depending on the height of the transition portion  192 ) vertical side  214  is defined between the outer edge  212  and the lower surface  53  of the block  190 . The height of the transition portion  192 , including slanted sides  194 ,  204 , can be lower, similar to that of block  20 , or can be higher, similar to that of block  150 . One or more gaps can also be provided in the transition portion  192  and lower portions  196 ,  206 . The block  190  can be otherwise configured similarly to block  20 ,  150 ,  170 , or other blocks. 
       FIG. 16  shows an example arrangement of two adjacent blocks  220 ,  222  configured similarly to block  190  and oriented similarly to that shown in  FIGS. 5-7 . Ends  224  of the blocks  220 ,  222  (e.g., second ends of each block) engage at facing vertical edges  226 . Similar to  FIGS. 5-7 , the blocks  220 ,  222  can form a straight line defined by the lower portions  194  while the upper portions  198  form a saw toothed pattern. 
     While groups of particular shapes of the twisted blocks  20 ,  150 ,  170 ,  190 ,  240  can be used for paving and/or edging, in some example embodiments differently sized and shaped twisted blocks can be combined.  FIGS. 17-19  show example arrangements of combined twisted blocks. For example,  FIG. 17  shows a partial surface covering including a twisted block  240  according to another embodiment of the invention, in which a lower portion  242  and an upper portion  244  both generally define a square. The width and length of the lower portion  242  are greater than those of the upper portion  244 . A transition portion includes slanted sides  245  disposed at each of a first side  246 , a second side  248 , a third side  250 , and a fourth side  252  of the block  240  (“first,” “second,” “third,” and “fourth” are used for purposes of illustration only). The blocks  240  can otherwise be configured similarly to blocks  20 ,  150 ,  170 ,  190 , or other blocks. In  FIG. 17 , the (square) block  240  is adjacent to (trapezoidal) twisted block  20 . In the example surface covering, the square block  240  and adjacent square blocks  240  provide a paver, while block  20  provides a border. 
       FIG. 18  shows a partial surface including two adjacent square blocks  240  edged by two adjacent trapezoidal twisted blocks  20 , and  FIG. 19  shows a surface covering in which a two-dimensional (e.g., square) pattern of square blocks is edged by a linear border formed by trapezoidal blocks  20 . As best viewed in  FIG. 19 , an interesting aesthetic is provided in which the upper surfaces  254  of the square blocks  240  form a saw toothed pattern, while the outer edge of the arranged square blocks (defined by the lower portions  242  of each block) form a square. Similarly, the upper surfaces of the trapezoidal blocks  20  as arranged in  FIG. 19  and the upper surfaces  254  of the square blocks  240  form a saw toothed pattern, while the outer edge of the trapezoidal blocks (defined by the lower portions  22  of each block) form a straight outer edge. Other twisted blocks, such as blocks  150 ,  170 ,  190 , etc. can be substituted for either the square blocks  240  used for paving or the trapezoidal blocks  20  used for edging. The sides of the square blocks  240  and the trapezoidal blocks  20  can be selected and configured to have the same length as shown in  FIG. 19 , or can have different lengths to produce different paving or edging patterns. 
       FIG. 20  shows an example partial surface covering including a pattern of rectangular twisted blocks  270 , in which a lower portion  272  and an upper portion  274  each generally define a rectangle. The width of the lower portion  272  is greater than that of the upper portion  274 . The upper portion defines a rectangle that is rotated or twisted with respect to the rectangle defined by the lower portion. The example rectangular blocks  270  have transition portions including slanted sides  276 ,  278  on sides and ends, respectively, configured similarly to the slanted portions  194 ,  204  in block  190 . As shown in  FIG. 20 , the rectangular twisted blocks  270  are arranged in a herring bone pattern for paving, while the slanted sides  276 ,  278  align to form substantially straight lines along an edge of these paving blocks. Other example arrangements for paving blocks include, but are not limited to, running bond, half bond, basket weave, and “I” formations. 
     Aligned trapezoidal twisted blocks  190  are provided to edge the surface covering, though in other embodiments blocks  20 ,  150 ,  170 , or other twisted blocks (or any combinations thereof) can be used. Also, in this example partial surface covering, the edges of the rectangular twisted blocks  270  and the trapezoidal twisted blocks  190  are not sized to match evenly. However, in other embodiments, edges can be sized to match evenly depending on particular desired surface covering and edging patterns. 
     Surface coverings in accordance with this disclosure, as shown for example in  FIGS. 19 and 20 , can be permeable, providing for water drainage. As discussed above with respect to the embodiments of  FIG. 14 , the transition and lower portions of the surface covering blocks (i.e., the feet of the blocks) can be provided with one or more gaps or channels so that surface covering has increased capacity to drain rain or storm water. Optionally, the gaps as well as spaces between adjacent upper portions of blocks can be filled with pervious material such as sand, gravel, or sod. The pervious material can be loose or bound, e.g., with a polymeric binder. See, e.g., U.S. patent application Ser. No. 14/105,679, filed Dec. 13, 2013, which is incorporated by reference in its entirety. 
       FIGS. 21-24  show a surface covering  300  including a plurality of square twisted blocks  302  according to another embodiment of the invention.  FIGS. 23-24  show an individual square twisted block  302 . The twisted blocks  302  include a transition portion that is disposed between a lower portion  306  ( FIGS. 22-24 ) and an upper portion  308 . The transition portion includes slanted sides  310 , similar to the slanted sides  245  of square block  240 . However, the bottoms of the slanted sides  310  in the square twisted blocks  302  are raised significantly with respect to a bottom surface  312  (or put another way, the lower portions have a significantly greater height). In a non-limiting example block  302 , for an overall block height of about 60 mm, the transition portion including slanted sides  310  has a depth of about ⅜″ below a top surface  314 . 
     This raised transition portion appears more like a visible chamfer, as opposed to a deep trough (as in square twisted block  240 ). The overall block  302  appears more like a conventional paver joint. Further, the twisted geometry provided by the lower and upper portions  306 ,  308  and slanted sides  310  is less likely to be obscured by material such as joint filling sand or polymeric sand. As shown in the top left block  302  in  FIG. 21 , and as also shown in  FIG. 23 , the upper portion  308  can include a textured top surface  314  and an optional beveled portion  318  similar to other example blocks disclosed herein. 
     Further embodiments of the invention can be provided with irregular surface features, which provide aesthetic benefits. The top surface and side surfaces can be molded or sculpted to add fissures, artificial joints, recesses, rounded protrusions, etc. to provide a natural rock-like appearance. In a conventional six-unit mold, the top shoe for each mold cavity can have a different configuration, i.e., introduce a top surface mold variation. Further, the side profile of a substantially vertical lower side face, substantially vertical upper side face with a slanted slide transition there between can be smoothly transitioned (without any sharp lines as shown in the drawings) or can be transitioned in an irregular manner. More specifically, the sides of the unit are preferably drafted, i.e., the sides taper or slant inwardly and progressively from bottom to top (based on the orientation of the unit in the mold). The degree of taper and slant of the side surfaces can vary in an irregular manner, both vertically and horizontally. Fissures, ledges, recesses and other natural rock features can be sculpted in the molds so the sides appear rock-like. See e.g., U.S. Design Patent Nos. D674,510 which is hereby incorporated by reference. This side molding feature is referred to herein as an “irregular draft” or as being “irregularly drafted.” 
     To further enhance the natural appearance of surface coverings and structures made with the units, the sides can be molded to match less than perfectly, i.e., that non-substantial gaps are formed between adjacent units, which gaps can vary in thickness. This is preferably accomplished by introducing minor variations in the sides of the upper portion so that gap between adjoining units varies in thickness without interfering with mating and interlocks of the base portions. “Mate” generally refers to fitting or associating suitably. 
     While preferred embodiments of twisted blocks have been herein illustrated and described, it is to be appreciated that certain changes, rearrangements and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.